From 678a67ce2d4fa12ef3a0ca262072319f1d6c0d71 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Thu, 20 Jan 2022 11:39:56 +0000
Subject: [PATCH 01/23] Invisible widgets now dont render

---
 examples/dev_sandbox.css | 49 +++++++++++++++++++++++++
 examples/dev_sandbox.py  | 32 ++++++++++++++++
 src/textual/dom.py       | 18 ++++++++-
 src/textual/layout.py    | 15 +++++++-
 src/textual/view.py      | 16 +++-----
 src/textual/widget.py    | 79 +++++++++++++++++-----------------------
 tests/test_widget.py     | 28 ++++++++++++++
 7 files changed, 180 insertions(+), 57 deletions(-)
 create mode 100644 examples/dev_sandbox.css
 create mode 100644 examples/dev_sandbox.py
 create mode 100644 tests/test_widget.py

diff --git a/examples/dev_sandbox.css b/examples/dev_sandbox.css
new file mode 100644
index 000000000..2e348e134
--- /dev/null
+++ b/examples/dev_sandbox.css
@@ -0,0 +1,49 @@
+/* CSS file for dev_sandbox.py */
+
+App > View {
+  docks: side=left/1;
+  text: on #20639b;
+}
+
+Widget:hover {
+  outline: heavy;
+  text: bold !important;
+}
+
+#sidebar {
+  text: #09312e on #3caea3;
+  dock: side;
+  width: 30;
+  offset-x: -100%;
+  transition: offset 500ms in_out_cubic;
+  border-right: outer #09312e;
+}
+
+#sidebar.-active {
+  offset-x: 0;
+}
+
+#header {
+  text: white on #173f5f;
+  height: 3;
+  border: hkey;
+}
+
+#header.-visible {
+  visibility: hidden;
+}
+
+#content {
+  text: white on #20639b;
+  border-bottom: hkey #0f2b41;
+  offset-y: -3;
+}
+
+#content.-content-visible {
+  visibility: hidden;
+}
+
+#footer {
+  text: #3a3009 on #f6d55c;
+  height: 3;
+}
diff --git a/examples/dev_sandbox.py b/examples/dev_sandbox.py
new file mode 100644
index 000000000..d53946fb3
--- /dev/null
+++ b/examples/dev_sandbox.py
@@ -0,0 +1,32 @@
+from rich.console import RenderableType
+from rich.panel import Panel
+
+from textual.app import App
+from textual.widget import Widget
+
+
+class PanelWidget(Widget):
+    def render(self) -> RenderableType:
+        return Panel("hello world!", title="Title")
+
+
+class BasicApp(App):
+    """Sandbox application used for testing/development by Textual developers"""
+
+    def on_load(self):
+        """Bind keys here."""
+        self.bind("tab", "toggle_class('#sidebar', '-active')")
+        self.bind("a", "toggle_class('#header', '-visible')")
+        self.bind("c", "toggle_class('#content', '-content-visible')")
+
+    def on_mount(self):
+        """Build layout here."""
+        self.mount(
+            header=Widget(),
+            content=PanelWidget(),
+            footer=Widget(),
+            sidebar=Widget(),
+        )
+
+
+BasicApp.run(css_file="test_app.css", watch_css=True, log="textual.log")
diff --git a/src/textual/dom.py b/src/textual/dom.py
index 8b17700ed..566f62858 100644
--- a/src/textual/dom.py
+++ b/src/textual/dom.py
@@ -9,7 +9,7 @@ from rich.style import Style
 from rich.tree import Tree
 
 from .css._error_tools import friendly_list
-from .css.constants import VALID_DISPLAY
+from .css.constants import VALID_DISPLAY, VALID_VISIBILITY
 from .css.errors import StyleValueError
 from .css.styles import Styles
 from .message_pump import MessagePump
@@ -160,6 +160,22 @@ class DOMNode(MessagePump):
                 f"expected {friendly_list(VALID_DISPLAY)})",
             )
 
+    @property
+    def visible(self) -> bool:
+        return self.styles.visibility != "hidden"
+
+    @visible.setter
+    def visible(self, new_value: bool) -> None:
+        if isinstance(new_value, bool):
+            self.styles.visibility = "visible" if new_value else "hidden"
+        elif new_value in VALID_VISIBILITY:
+            self.styles.visibility = new_value
+        else:
+            raise StyleValueError(
+                f"invalid value for visibility (received {new_value!r}, "
+                f"expected {friendly_list(VALID_VISIBILITY)})"
+            )
+
     @property
     def z(self) -> tuple[int, ...]:
         """Get the z index tuple for this node.
diff --git a/src/textual/layout.py b/src/textual/layout.py
index 72f5e1422..28bb1dce5 100644
--- a/src/textual/layout.py
+++ b/src/textual/layout.py
@@ -199,6 +199,7 @@ class Layout(ABC):
         raise NoWidget(f"No widget under screen coordinate ({x}, {y})")
 
     def get_style_at(self, x: int, y: int) -> Style:
+        """Get the Style at the given cell or Style.null()"""
         try:
             widget, region = self.get_widget_at(x, y)
         except NoWidget:
@@ -217,6 +218,18 @@ class Layout(ABC):
         return Style.null()
 
     def get_widget_region(self, widget: Widget) -> Region:
+        """Get the Region of a Widget contained in this Layout.
+
+        Args:
+            widget: The Widget in this layout you wish to know the Region of.
+
+        Raises:
+            KeyError: If the Widget is not contained in this Layout.
+
+        Returns:
+            Region: The Region of the Widget.
+
+        """
         try:
             region, *_ = self.map[widget]
         except KeyError:
@@ -270,7 +283,7 @@ class Layout(ABC):
 
         for widget, region, _order, clip in widget_regions:
 
-            if not widget.is_visual:
+            if not (widget.is_visual and widget.visible):
                 continue
 
             lines = widget._get_lines()
diff --git a/src/textual/view.py b/src/textual/view.py
index d6cd03784..c91e8526f 100644
--- a/src/textual/view.py
+++ b/src/textual/view.py
@@ -1,26 +1,22 @@
 from __future__ import annotations
 
-from itertools import chain
-from typing import Callable, Iterable, ClassVar, TYPE_CHECKING
+from typing import Callable, Iterable, TYPE_CHECKING
 
-from rich.console import RenderableType
 import rich.repr
+from rich.console import RenderableType
 from rich.style import Style
 
-from . import events
 from . import errors
-from . import log
+from . import events
 from . import messages
+from .geometry import Size, Offset, Region
 from .layout import Layout, NoWidget, WidgetPlacement
 from .layouts.factory import get_layout
-from .geometry import Size, Offset, Region
 from .reactive import Reactive, watch
-
-from .widget import Widget, Widget
-
+from .widget import Widget
 
 if TYPE_CHECKING:
-    from .app import App
+    pass
 
 
 class LayoutProperty:
diff --git a/src/textual/widget.py b/src/textual/widget.py
index 51c7e97ab..94d768129 100644
--- a/src/textual/widget.py
+++ b/src/textual/widget.py
@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from logging import PercentStyle, getLogger
+from logging import getLogger
 from typing import (
     Any,
     Awaitable,
@@ -11,35 +11,29 @@ from typing import (
     NamedTuple,
     cast,
 )
-import rich.repr
-from rich import box
-from rich.align import Align
-from rich.console import Console, RenderableType, ConsoleOptions
-from rich.measure import Measurement
-from rich.panel import Panel
-from rich.padding import Padding
-from rich.pretty import Pretty
-from rich.segment import Segment
-from rich.style import Style, StyleType
-from rich.styled import Styled
-from rich.text import Text, TextType
 
-from . import events
+import rich.repr
+from rich.align import Align
+from rich.console import Console, RenderableType
+from rich.padding import Padding
+from rich.style import Style
+from rich.styled import Styled
+from rich.text import Text
+
 from . import errors
+from . import events
 from ._animator import BoundAnimator
-from ._border import Border, BORDER_STYLES
+from ._border import Border
 from ._callback import invoke
-from .blank import Blank
-from .dom import DOMNode
 from ._context import active_app
-from .geometry import Size, Spacing, SpacingDimensions
+from ._types import Lines
+from .dom import DOMNode
+from .geometry import Size, Spacing
 from .message import Message
 from .messages import Layout, Update
-from .reactive import Reactive, watch
-from ._types import Lines
+from .reactive import watch
 
 if TYPE_CHECKING:
-    from .app import App
     from .view import View
 
 log = getLogger("rich")
@@ -163,34 +157,29 @@ class Widget(DOMNode):
         styles = self.styles
         parent_text_style = self.parent.text_style
 
-        if styles.visibility == "hidden":
-            renderable = Blank(parent_text_style)
-        else:
-            text_style = styles.text
-            renderable_text_style = parent_text_style + text_style
-            if renderable_text_style:
-                renderable = Styled(renderable, renderable_text_style)
+        text_style = styles.text
+        renderable_text_style = parent_text_style + text_style
+        if renderable_text_style:
+            renderable = Styled(renderable, renderable_text_style)
 
-            if styles.has_padding:
-                renderable = Padding(
-                    renderable, styles.padding, style=renderable_text_style
-                )
+        if styles.has_padding:
+            renderable = Padding(
+                renderable, styles.padding, style=renderable_text_style
+            )
 
-            if styles.has_border:
-                renderable = Border(
-                    renderable, styles.border, style=renderable_text_style
-                )
+        if styles.has_border:
+            renderable = Border(renderable, styles.border, style=renderable_text_style)
 
-            if styles.has_margin:
-                renderable = Padding(renderable, styles.margin, style=parent_text_style)
+        if styles.has_margin:
+            renderable = Padding(renderable, styles.margin, style=parent_text_style)
 
-            if styles.has_outline:
-                renderable = Border(
-                    renderable,
-                    styles.outline,
-                    outline=True,
-                    style=renderable_text_style,
-                )
+        if styles.has_outline:
+            renderable = Border(
+                renderable,
+                styles.outline,
+                outline=True,
+                style=renderable_text_style,
+            )
 
         return renderable
 
diff --git a/tests/test_widget.py b/tests/test_widget.py
new file mode 100644
index 000000000..7eee43a54
--- /dev/null
+++ b/tests/test_widget.py
@@ -0,0 +1,28 @@
+import pytest
+
+from textual.css.errors import StyleValueError
+from textual.widget import Widget
+
+
+@pytest.mark.parametrize(
+    "set_val, get_val, style_str", [
+        [True, True, "visible"],
+        [False, False, "hidden"],
+        ["hidden", False, "hidden"],
+        ["visible", True, "visible"],
+    ])
+def test_widget_set_visible_true(set_val, get_val, style_str):
+    widget = Widget()
+    widget.visible = set_val
+
+    assert widget.visible is get_val
+    assert widget.styles.visibility == style_str
+
+
+def test_widget_set_visible_invalid_string():
+    widget = Widget()
+
+    with pytest.raises(StyleValueError):
+        widget.visible = "nope! no widget for me!"
+
+    assert widget.visible

From 1e92b08e1b67900605fcc3851e93e62b5f7a01f9 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Thu, 20 Jan 2022 13:05:58 +0000
Subject: [PATCH 02/23] Docstring improvements

---
 src/textual/layout.py | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/textual/layout.py b/src/textual/layout.py
index 28bb1dce5..b07a96424 100644
--- a/src/textual/layout.py
+++ b/src/textual/layout.py
@@ -199,7 +199,15 @@ class Layout(ABC):
         raise NoWidget(f"No widget under screen coordinate ({x}, {y})")
 
     def get_style_at(self, x: int, y: int) -> Style:
-        """Get the Style at the given cell or Style.null()"""
+        """Get the Style at the given cell or Style.null()
+
+        Args:
+            x (int): X position within the Layout
+            y (int): Y position within the Layout
+
+        Returns:
+            Style: The Style at the cell (x, y) within the Layout
+        """
         try:
             widget, region = self.get_widget_at(x, y)
         except NoWidget:
@@ -221,7 +229,7 @@ class Layout(ABC):
         """Get the Region of a Widget contained in this Layout.
 
         Args:
-            widget: The Widget in this layout you wish to know the Region of.
+            widget (Widget): The Widget in this layout you wish to know the Region of.
 
         Raises:
             KeyError: If the Widget is not contained in this Layout.

From e2fd92bda228c9f62e49580ac8b5fb1d5f97a154 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Thu, 20 Jan 2022 14:47:37 +0000
Subject: [PATCH 03/23] Margin space is now not rendered as solid colour

---
 src/textual/css/_styles_builder.py |  2 +-
 src/textual/geometry.py            | 18 ++++++++++++++++++
 src/textual/view.py                | 19 ++++++++++++++++++-
 src/textual/widget.py              |  3 ---
 tests/test_geometry.py             |  8 +++++++-
 5 files changed, 44 insertions(+), 6 deletions(-)

diff --git a/src/textual/css/_styles_builder.py b/src/textual/css/_styles_builder.py
index 17349a04f..871d21f39 100644
--- a/src/textual/css/_styles_builder.py
+++ b/src/textual/css/_styles_builder.py
@@ -128,7 +128,7 @@ class StylesBuilder:
         append = space.append
         for token in tokens:
             (token_name, value, _, _, location) = token
-            if token_name == "scalar":
+            if token_name in ("number", "scalar"):
                 try:
                     append(int(value))
                 except ValueError:
diff --git a/src/textual/geometry.py b/src/textual/geometry.py
index b9fcb2f52..d89075397 100644
--- a/src/textual/geometry.py
+++ b/src/textual/geometry.py
@@ -415,6 +415,24 @@ class Region(NamedTuple):
         )
         return new_region
 
+    def shrink(self, margin: Spacing) -> Region:
+        """Shrink a region by pushing each edge inwards.
+
+        Args:
+            margin (Spacing): Defines how many cells to shrink the Region by at each edge.
+
+        Returns:
+            Region: The new, smaller region.
+        """
+        _clamp = clamp
+        top, right, bottom, left = margin
+        return Region(
+            x=_clamp(self.x + left, 0, self.width),
+            y=_clamp(self.y + top, 0, self.height),
+            width=_clamp(self.width - left - right, 0, self.width),
+            height=_clamp(self.height - top - bottom, 0, self.height),
+        )
+
     def intersection(self, region: Region) -> Region:
         """Get that covers both regions.
 
diff --git a/src/textual/view.py b/src/textual/view.py
index d6cd03784..2eb589352 100644
--- a/src/textual/view.py
+++ b/src/textual/view.py
@@ -114,7 +114,24 @@ class View(Widget):
         cached_size, cached_scroll, arrangement = self._cached_arrangement
         if cached_size == size and cached_scroll == scroll:
             return arrangement
-        arrangement = list(self._layout.arrange(self, size, scroll))
+
+        arrangement = []
+        placements = self._layout.arrange(self, size, scroll)
+        for placement in placements:
+            region, widget, order = placement
+            styles = widget.styles
+            if styles.has_margin:
+                margin = styles.margin
+                arrangement.append(
+                    WidgetPlacement(
+                        region=region.shrink(margin),
+                        widget=widget,
+                        order=order,
+                    )
+                )
+            else:
+                arrangement.append(placement)
+
         self._cached_arrangement = (size, scroll, arrangement)
         return arrangement
 
diff --git a/src/textual/widget.py b/src/textual/widget.py
index 51c7e97ab..0f81a7d15 100644
--- a/src/textual/widget.py
+++ b/src/textual/widget.py
@@ -181,9 +181,6 @@ class Widget(DOMNode):
                     renderable, styles.border, style=renderable_text_style
                 )
 
-            if styles.has_margin:
-                renderable = Padding(renderable, styles.margin, style=parent_text_style)
-
             if styles.has_outline:
                 renderable = Border(
                     renderable,
diff --git a/tests/test_geometry.py b/tests/test_geometry.py
index ffaded07b..2bfbc695d 100644
--- a/tests/test_geometry.py
+++ b/tests/test_geometry.py
@@ -1,6 +1,6 @@
 import pytest
 
-from textual.geometry import clamp, Offset, Size, Region
+from textual.geometry import clamp, Offset, Size, Region, Spacing
 
 
 def test_dimensions_region():
@@ -173,6 +173,12 @@ def test_clip():
     assert Region(10, 10, 20, 30).clip(20, 25) == Region(10, 10, 10, 15)
 
 
+def test_region_shrink():
+    margin = Spacing(top=1, right=2, bottom=3, left=4)
+    region = Region(x=10, y=10, width=50, height=50)
+    assert region.shrink(margin) == Region(x=14, y=11, width=44, height=46)
+
+
 def test_region_intersection():
     assert Region(0, 0, 100, 50).intersection(Region(10, 10, 10, 10)) == Region(
         10, 10, 10, 10

From 8b24a476f097bcc2ec387ed54c2fadd8b451cbc5 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Thu, 20 Jan 2022 14:50:35 +0000
Subject: [PATCH 04/23] Remove redundant code, fix incorrect docstring

---
 src/textual/layout.py | 2 +-
 src/textual/view.py   | 3 ---
 2 files changed, 1 insertion(+), 4 deletions(-)

diff --git a/src/textual/layout.py b/src/textual/layout.py
index b07a96424..8542e5942 100644
--- a/src/textual/layout.py
+++ b/src/textual/layout.py
@@ -232,7 +232,7 @@ class Layout(ABC):
             widget (Widget): The Widget in this layout you wish to know the Region of.
 
         Raises:
-            KeyError: If the Widget is not contained in this Layout.
+            NoWidget: If the Widget is not contained in this Layout.
 
         Returns:
             Region: The Region of the Widget.
diff --git a/src/textual/view.py b/src/textual/view.py
index c91e8526f..9c07ca110 100644
--- a/src/textual/view.py
+++ b/src/textual/view.py
@@ -15,9 +15,6 @@ from .layouts.factory import get_layout
 from .reactive import Reactive, watch
 from .widget import Widget
 
-if TYPE_CHECKING:
-    pass
-
 
 class LayoutProperty:
     def __get__(self, obj: View, objtype: type[View] | None = None) -> str:

From 13d7580291882c22acbb65c514c2edb42edb2a60 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Thu, 20 Jan 2022 15:04:37 +0000
Subject: [PATCH 05/23] Remove unused import

---
 src/textual/view.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/textual/view.py b/src/textual/view.py
index 9c07ca110..220551eb7 100644
--- a/src/textual/view.py
+++ b/src/textual/view.py
@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from typing import Callable, Iterable, TYPE_CHECKING
+from typing import Callable, Iterable
 
 import rich.repr
 from rich.console import RenderableType

From c59dff5c1577a3b70b7e961c43969c465d3b8d58 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Thu, 20 Jan 2022 17:12:00 +0000
Subject: [PATCH 06/23] Move logic for applying margin to widgets into
 WidgetPlacement

---
 examples/basic.py       |  2 +-
 src/textual/geometry.py |  9 +++++----
 src/textual/layout.py   | 11 +++++++++++
 src/textual/view.py     | 24 ++++++------------------
 4 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/examples/basic.py b/examples/basic.py
index d06ac0765..d16baab6a 100644
--- a/examples/basic.py
+++ b/examples/basic.py
@@ -13,10 +13,10 @@ class BasicApp(App):
     def on_mount(self):
         """Build layout here."""
         self.mount(
+            sidebar=Widget(),
             header=Widget(),
             content=Widget(),
             footer=Widget(),
-            sidebar=Widget(),
         )
 
 
diff --git a/src/textual/geometry.py b/src/textual/geometry.py
index d89075397..004964ba9 100644
--- a/src/textual/geometry.py
+++ b/src/textual/geometry.py
@@ -426,11 +426,12 @@ class Region(NamedTuple):
         """
         _clamp = clamp
         top, right, bottom, left = margin
+        x, y, width, height = self
         return Region(
-            x=_clamp(self.x + left, 0, self.width),
-            y=_clamp(self.y + top, 0, self.height),
-            width=_clamp(self.width - left - right, 0, self.width),
-            height=_clamp(self.height - top - bottom, 0, self.height),
+            x=_clamp(x + left, 0, width),
+            y=_clamp(y + top, 0, height),
+            width=_clamp(width - left - right, 0, width),
+            height=_clamp(height - top - bottom, 0, height),
         )
 
     def intersection(self, region: Region) -> Region:
diff --git a/src/textual/layout.py b/src/textual/layout.py
index 72f5e1422..54c1eac32 100644
--- a/src/textual/layout.py
+++ b/src/textual/layout.py
@@ -55,6 +55,17 @@ class WidgetPlacement(NamedTuple):
     widget: Widget | None = None
     order: int = 0
 
+    def apply_margin(self) -> "WidgetPlacement":
+        region, widget, order = self
+        styles = widget.styles
+        if styles.has_margin:
+            return WidgetPlacement(
+                region=region.shrink(styles.margin),
+                widget=widget,
+                order=order,
+            )
+        return self
+
 
 @rich.repr.auto
 class LayoutUpdate:
diff --git a/src/textual/view.py b/src/textual/view.py
index 2eb589352..b680e4a33 100644
--- a/src/textual/view.py
+++ b/src/textual/view.py
@@ -115,25 +115,13 @@ class View(Widget):
         if cached_size == size and cached_scroll == scroll:
             return arrangement
 
-        arrangement = []
-        placements = self._layout.arrange(self, size, scroll)
-        for placement in placements:
-            region, widget, order = placement
-            styles = widget.styles
-            if styles.has_margin:
-                margin = styles.margin
-                arrangement.append(
-                    WidgetPlacement(
-                        region=region.shrink(margin),
-                        widget=widget,
-                        order=order,
-                    )
-                )
-            else:
-                arrangement.append(placement)
+        placements = [
+            placement.apply_margin()
+            for placement in self._layout.arrange(self, size, scroll)
+        ]
 
-        self._cached_arrangement = (size, scroll, arrangement)
-        return arrangement
+        self._cached_arrangement = (size, scroll, placements)
+        return placements
 
     async def handle_update(self, message: messages.Update) -> None:
         if self.is_root_view:

From 8406718cf3ec41cd6a83929c68f8b8df05c36b89 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Thu, 20 Jan 2022 17:16:26 +0000
Subject: [PATCH 07/23] Revert basic.py back to previous state

---
 examples/basic.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/basic.py b/examples/basic.py
index d16baab6a..d06ac0765 100644
--- a/examples/basic.py
+++ b/examples/basic.py
@@ -13,10 +13,10 @@ class BasicApp(App):
     def on_mount(self):
         """Build layout here."""
         self.mount(
-            sidebar=Widget(),
             header=Widget(),
             content=Widget(),
             footer=Widget(),
+            sidebar=Widget(),
         )
 
 

From 5773e39845839146bef5d1a94c13da2661736ee0 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Fri, 21 Jan 2022 12:33:35 +0000
Subject: [PATCH 08/23] Move LayoutProperty into styles, add some comments

---
 examples/basic.css                   |  1 +
 src/textual/app.py                   |  2 +-
 src/textual/css/_style_properties.py | 17 +++++++++++++++++
 src/textual/css/styles.py            |  7 ++++++-
 src/textual/css/stylesheet.py        | 12 ++++++++++--
 src/textual/view.py                  | 19 ++-----------------
 6 files changed, 37 insertions(+), 21 deletions(-)

diff --git a/examples/basic.css b/examples/basic.css
index efafe797e..279f6e520 100644
--- a/examples/basic.css
+++ b/examples/basic.css
@@ -1,6 +1,7 @@
 /* CSS file for basic.py */
 
 App > View {
+  layout: dock;
   docks: side=left/1;
   text: on #20639b;
 }
diff --git a/src/textual/app.py b/src/textual/app.py
index 0e6dee254..6f181cf89 100644
--- a/src/textual/app.py
+++ b/src/textual/app.py
@@ -510,7 +510,7 @@ class App(DOMNode):
         # Handle input events that haven't been forwarded
         # If the event has been forwarded it may have bubbled up back to the App
         if isinstance(event, events.Mount):
-            view = View()
+            view = View(id="_root")
             self.register(self, view)
             await self.push_view(view)
             await super().on_event(event)
diff --git a/src/textual/css/_style_properties.py b/src/textual/css/_style_properties.py
index 3ed32ee8b..fdb9b31a9 100644
--- a/src/textual/css/_style_properties.py
+++ b/src/textual/css/_style_properties.py
@@ -28,6 +28,7 @@ from .constants import NULL_SPACING
 from .errors import StyleTypeError, StyleValueError
 from .transition import Transition
 from ._error_tools import friendly_list
+from ..layouts.factory import get_layout
 
 if TYPE_CHECKING:
     from .styles import Styles
@@ -290,6 +291,22 @@ class DockProperty:
         return spacing
 
 
+class LayoutProperty:
+    def __set_name__(self, owner: Styles, name: str) -> None:
+        self._internal_name = f"_rule_{name}"
+
+    def __get__(self, obj: Styles, objtype: type[Styles] | None = None) -> str:
+        return getattr(obj, self._internal_name) or ""
+
+    def __set__(self, obj: Styles, layout: str | Styles):
+        obj.refresh(True)
+        if isinstance(layout, str):
+            new_layout = get_layout(layout)
+        else:
+            new_layout = layout
+        self._layout = new_layout
+
+
 class OffsetProperty:
     def __set_name__(self, owner: Styles, name: str) -> None:
         self._internal_name = f"_rule_{name}"
diff --git a/src/textual/css/styles.py b/src/textual/css/styles.py
index 533167347..09510ae78 100644
--- a/src/textual/css/styles.py
+++ b/src/textual/css/styles.py
@@ -42,6 +42,7 @@ from ._style_properties import (
     StyleProperty,
     StyleFlagsProperty,
     TransitionsProperty,
+    LayoutProperty,
 )
 from .types import Display, Edge, Visibility
 
@@ -110,7 +111,7 @@ class Styles:
 
     display = StringProperty(VALID_DISPLAY, "block")
     visibility = StringProperty(VALID_VISIBILITY, "visible")
-    layout = StringProperty(VALID_LAYOUT, "dock")
+    layout = LayoutProperty()
 
     text = StyleProperty()
     text_color = ColorProperty()
@@ -279,6 +280,10 @@ class Styles:
                         )
                 else:
                     setattr(styles, f"_rule_{key}", value)
+
+        if self.node.id == "_root":
+            log("_root.styles.layout =", self.node.styles.layout)
+
         if self.node is not None:
             self.node.on_style_change()
 
diff --git a/src/textual/css/stylesheet.py b/src/textual/css/stylesheet.py
index 05704b782..802c86fbb 100644
--- a/src/textual/css/stylesheet.py
+++ b/src/textual/css/stylesheet.py
@@ -108,18 +108,24 @@ class Stylesheet:
                 yield selector_set.specificity
 
     def apply(self, node: DOMNode) -> None:
+        # Dictionary of rule attribute names e.g. "text_background" to list of tuples.
+        # The tuples contain the rule specificity, and the value for that rule.
+        # We can use this to determine, for a given rule, whether we should apply it
+        # or not by examining the specificity. If we have two rules for the
+        # same attribute, then we can choose the most specific rule and use that.
         rule_attributes: dict[str, list[tuple[Specificity4, object]]]
         rule_attributes = defaultdict(list)
 
         _check_rule = self._check_rule
 
+        # TODO: The line below breaks inline styles and animations
         node.styles.reset()
 
-        # Get the default node CSS rules
+        # Collect default node CSS rules
         for key, default_specificity, value in node._default_rules:
             rule_attributes[key].append((default_specificity, value))
 
-        # Apply styles on top of the default node CSS rules
+        # Collect the rules defined in the stylesheet
         for rule in self.rules:
             for specificity in _check_rule(rule, node):
                 for key, rule_specificity, value in rule.styles.extract_rules(
@@ -127,12 +133,14 @@ class Stylesheet:
                 ):
                     rule_attributes[key].append((rule_specificity, value))
 
+        # For each rule declared for this node, keep only the most specific one
         get_first_item = itemgetter(0)
         node_rules = [
             (name, max(specificity_rules, key=get_first_item)[1])
             for name, specificity_rules in rule_attributes.items()
         ]
 
+        log(node.id, node_rules)
         node.styles.apply_rules(node_rules)
 
     def update(self, root: DOMNode) -> None:
diff --git a/src/textual/view.py b/src/textual/view.py
index d6cd03784..f4f17e92f 100644
--- a/src/textual/view.py
+++ b/src/textual/view.py
@@ -16,26 +16,13 @@ from .layouts.factory import get_layout
 from .geometry import Size, Offset, Region
 from .reactive import Reactive, watch
 
-from .widget import Widget, Widget
+from .widget import Widget
 
 
 if TYPE_CHECKING:
     from .app import App
 
 
-class LayoutProperty:
-    def __get__(self, obj: View, objtype: type[View] | None = None) -> str:
-        return obj._layout.name
-
-    def __set__(self, obj: View, layout: str | Layout) -> str:
-        if isinstance(layout, str):
-            new_layout = get_layout(layout)
-        else:
-            new_layout = layout
-        self._layout = new_layout
-        return self._layout.name
-
-
 @rich.repr.auto
 class View(Widget):
 
@@ -45,7 +32,7 @@ class View(Widget):
     """
 
     def __init__(self, name: str | None = None, id: str | None = None) -> None:
-
+        # TODO: Get rid of this, replace usages with layout from Styles object
         from .layouts.dock import DockLayout
 
         self._layout: Layout = DockLayout()
@@ -69,8 +56,6 @@ class View(Widget):
             cls.layout_factory = layout
         super().__init_subclass__(**kwargs)
 
-    layout = LayoutProperty()
-
     background: Reactive[str] = Reactive("")
     scroll_x: Reactive[int] = Reactive(0)
     scroll_y: Reactive[int] = Reactive(0)

From c6429e51acfcf805aa39ce962b8b1bd49d739b23 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Fri, 21 Jan 2022 13:18:39 +0000
Subject: [PATCH 09/23] Fixing transitive imports and circular imports

---
 src/textual/app.py                   | 43 ++++++++++------------------
 src/textual/css/_style_properties.py |  3 +-
 src/textual/css/model.py             |  7 +++--
 src/textual/dom.py                   |  8 ++----
 src/textual/layouts/dock.py          |  9 +-----
 src/textual/layouts/factory.py       | 15 ++++------
 src/textual/layouts/grid.py          |  8 ++----
 src/textual/layouts/vertical.py      |  1 -
 src/textual/scrollbar.py             | 10 +++----
 src/textual/view.py                  |  1 -
 src/textual/widget.py                | 35 ++++++++++------------
 src/textual/widgets/_placeholder.py  |  3 +-
 12 files changed, 56 insertions(+), 87 deletions(-)

diff --git a/src/textual/app.py b/src/textual/app.py
index 6f181cf89..afdb99892 100644
--- a/src/textual/app.py
+++ b/src/textual/app.py
@@ -1,50 +1,44 @@
 from __future__ import annotations
-import os
 
+import os
 import asyncio
 
-from typing import Any, Callable, ClassVar, Iterable, Type, TypeVar
 import warnings
-
-from rich.control import Control
+from typing import Any, Callable, Iterable, Type, TypeVar
 
 import rich.repr
-from rich.screen import Screen
 from rich.console import Console, RenderableType
+from rich.control import Control
 from rich.measure import Measurement
-
+from rich.screen import Screen
 from rich.traceback import Traceback
 
-
-from . import events
 from . import actions
-from .dom import DOMNode
-from ._animator import Animator
-from .binding import Bindings, NoBinding
-from .geometry import Offset, Region, Size
+from . import events
 from . import log
+from . import messages
+from ._animator import Animator
 from ._callback import invoke
 from ._context import active_app
-from .css.stylesheet import Stylesheet, StylesheetParseError, StylesheetError
 from ._event_broker import extract_handler_actions, NoHandler
+from ._linux_driver import LinuxDriver
+from ._profile import timer
+from .binding import Bindings, NoBinding
+from .css.stylesheet import Stylesheet, StylesheetParseError, StylesheetError
+from .dom import DOMNode
 from .driver import Driver
 from .file_monitor import FileMonitor
-
+from .geometry import Offset, Region, Size
 from .layouts.dock import DockLayout, Dock
-from ._linux_driver import LinuxDriver
-from ._types import MessageTarget
-from . import messages
 from .message_pump import MessagePump
-from ._profile import timer
+from .reactive import Reactive
 from .view import View
 from .views import DockView
-from .widget import Widget, Reactive
-
+from .widget import Widget
 
 # asyncio will warn against resources not being cleared
 warnings.simplefilter("always", ResourceWarning)
 
-
 LayoutDefinition = "dict[str, Any]"
 
 ViewType = TypeVar("ViewType", bound=View)
@@ -638,17 +632,11 @@ class App(DOMNode):
 
 if __name__ == "__main__":
     import asyncio
-    from logging import FileHandler
-
-    from rich.panel import Panel
 
     from .widgets import Header
     from .widgets import Footer
 
     from .widgets import Placeholder
-    from .scrollbar import ScrollBar
-
-    from rich.markdown import Markdown
 
     # from .widgets.scroll_view import ScrollView
 
@@ -672,7 +660,6 @@ if __name__ == "__main__":
             self.show_bar = not self.show_bar
 
         async def on_mount(self, event: events.Mount) -> None:
-
             view = await self.push_view(DockView())
 
             header = Header()
diff --git a/src/textual/css/_style_properties.py b/src/textual/css/_style_properties.py
index fdb9b31a9..5b1c11307 100644
--- a/src/textual/css/_style_properties.py
+++ b/src/textual/css/_style_properties.py
@@ -28,7 +28,6 @@ from .constants import NULL_SPACING
 from .errors import StyleTypeError, StyleValueError
 from .transition import Transition
 from ._error_tools import friendly_list
-from ..layouts.factory import get_layout
 
 if TYPE_CHECKING:
     from .styles import Styles
@@ -299,6 +298,8 @@ class LayoutProperty:
         return getattr(obj, self._internal_name) or ""
 
     def __set__(self, obj: Styles, layout: str | Styles):
+        from ..layouts.factory import get_layout
+
         obj.refresh(True)
         if isinstance(layout, str):
             new_layout = get_layout(layout)
diff --git a/src/textual/css/model.py b/src/textual/css/model.py
index 2dd7a5cc0..64dfb4ef6 100644
--- a/src/textual/css/model.py
+++ b/src/textual/css/model.py
@@ -5,14 +5,15 @@ import rich.repr
 
 from dataclasses import dataclass, field
 from enum import Enum
-from typing import Iterable
+from typing import Iterable, TYPE_CHECKING
 
-from .. import log
-from ..dom import DOMNode
 from .styles import Styles
 from .tokenize import Token
 from .types import Specificity3
 
+if TYPE_CHECKING:
+    from ..dom import DOMNode
+
 
 class SelectorType(Enum):
     UNIVERSAL = 1
diff --git a/src/textual/dom.py b/src/textual/dom.py
index 8b17700ed..50b96675d 100644
--- a/src/textual/dom.py
+++ b/src/textual/dom.py
@@ -1,24 +1,22 @@
 from __future__ import annotations
 
-from typing import Any, cast, Iterable, Iterator, TYPE_CHECKING
+from typing import Iterable, Iterator, TYPE_CHECKING
 
-from rich.highlighter import ReprHighlighter
 import rich.repr
+from rich.highlighter import ReprHighlighter
 from rich.pretty import Pretty
 from rich.style import Style
 from rich.tree import Tree
 
+from ._node_list import NodeList
 from .css._error_tools import friendly_list
 from .css.constants import VALID_DISPLAY
 from .css.errors import StyleValueError
 from .css.styles import Styles
 from .message_pump import MessagePump
-from ._node_list import NodeList
-
 
 if TYPE_CHECKING:
     from .css.query import DOMQuery
-    from .widget import Widget
 
 
 class NoParent(Exception):
diff --git a/src/textual/layouts/dock.py b/src/textual/layouts/dock.py
index 16b4f152b..281c53f5f 100644
--- a/src/textual/layouts/dock.py
+++ b/src/textual/layouts/dock.py
@@ -5,14 +5,10 @@ from collections import defaultdict
 from dataclasses import dataclass
 from typing import Iterable, TYPE_CHECKING, NamedTuple, Sequence
 
-
-from .. import log
-from ..dom import DOMNode
 from .._layout_resolve import layout_resolve
+from ..css.types import Edge
 from ..geometry import Offset, Region, Size
 from ..layout import Layout, WidgetPlacement
-from ..layout_map import LayoutMap
-from ..css.types import Edge
 from ..widget import Widget
 
 if sys.version_info >= (3, 8):
@@ -20,12 +16,9 @@ if sys.version_info >= (3, 8):
 else:
     from typing_extensions import Literal
 
-
 if TYPE_CHECKING:
-    from ..widget import Widget
     from ..view import View
 
-
 DockEdge = Literal["top", "right", "bottom", "left"]
 
 
diff --git a/src/textual/layouts/factory.py b/src/textual/layouts/factory.py
index a6718f427..fb491e578 100644
--- a/src/textual/layouts/factory.py
+++ b/src/textual/layouts/factory.py
@@ -1,19 +1,15 @@
-from __future__ import annotations
+from ..layouts.dock import DockLayout
+from ..layouts.grid import GridLayout
+from ..layouts.vertical import VerticalLayout
 
-from ..layout import Layout
-from .dock import DockLayout
-from .grid import GridLayout
-from .vertical import VerticalLayout
+LAYOUT_MAP = {"dock": DockLayout, "grid": GridLayout, "vertical": VerticalLayout}
 
 
 class MissingLayout(Exception):
     pass
 
 
-LAYOUT_MAP = {"dock": DockLayout, "grid": GridLayout, "vertical": VerticalLayout}
-
-
-def get_layout(name: str) -> Layout:
+def get_layout(name: str):
     """Get a named layout object.
 
     Args:
@@ -25,6 +21,7 @@ def get_layout(name: str) -> Layout:
     Returns:
         Layout: A layout object.
     """
+
     layout_class = LAYOUT_MAP.get(name)
     if layout_class is None:
         raise MissingLayout("no layout called {name!r}")
diff --git a/src/textual/layouts/grid.py b/src/textual/layouts/grid.py
index f53127190..276cd417f 100644
--- a/src/textual/layouts/grid.py
+++ b/src/textual/layouts/grid.py
@@ -1,18 +1,16 @@
 from __future__ import annotations
 
+import sys
 from collections import defaultdict
 from dataclasses import dataclass
-from operator import itemgetter
-from logging import getLogger
 from itertools import cycle, product
-import sys
+from logging import getLogger
+from operator import itemgetter
 from typing import Iterable, NamedTuple, TYPE_CHECKING
 
 from .._layout_resolve import layout_resolve
 from ..geometry import Size, Offset, Region
 from ..layout import Layout, WidgetPlacement
-from ..widget import Widget
-
 
 if TYPE_CHECKING:
     from ..widget import Widget
diff --git a/src/textual/layouts/vertical.py b/src/textual/layouts/vertical.py
index 247909c67..75a54df73 100644
--- a/src/textual/layouts/vertical.py
+++ b/src/textual/layouts/vertical.py
@@ -4,7 +4,6 @@ from typing import Iterable, TYPE_CHECKING
 
 from ..geometry import Offset, Region, Size, Spacing, SpacingDimensions
 from ..layout import Layout, WidgetPlacement
-from ..widget import Widget
 from .._loop import loop_last
 
 if TYPE_CHECKING:
diff --git a/src/textual/scrollbar.py b/src/textual/scrollbar.py
index 3a5590b0f..d932359d7 100644
--- a/src/textual/scrollbar.py
+++ b/src/textual/scrollbar.py
@@ -1,17 +1,17 @@
 from __future__ import annotations
 
-
 import rich.repr
 from rich.color import Color
-from rich.console import Console, ConsoleOptions, RenderResult, RenderableType
-from rich.segment import Segment, Segments
+from rich.console import ConsoleOptions, RenderResult, RenderableType
+from rich.segment import Segment
 from rich.style import Style, StyleType
 
+from textual.reactive import Reactive
 from . import events
-from .geometry import Offset
 from ._types import MessageTarget
+from .geometry import Offset
 from .message import Message
-from .widget import Reactive, Widget
+from .widget import Widget
 
 
 @rich.repr.auto
diff --git a/src/textual/view.py b/src/textual/view.py
index f4f17e92f..3d7df4112 100644
--- a/src/textual/view.py
+++ b/src/textual/view.py
@@ -12,7 +12,6 @@ from . import errors
 from . import log
 from . import messages
 from .layout import Layout, NoWidget, WidgetPlacement
-from .layouts.factory import get_layout
 from .geometry import Size, Offset, Region
 from .reactive import Reactive, watch
 
diff --git a/src/textual/widget.py b/src/textual/widget.py
index 51c7e97ab..b816abda3 100644
--- a/src/textual/widget.py
+++ b/src/textual/widget.py
@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from logging import PercentStyle, getLogger
+from logging import getLogger
 from typing import (
     Any,
     Awaitable,
@@ -11,35 +11,30 @@ from typing import (
     NamedTuple,
     cast,
 )
-import rich.repr
-from rich import box
-from rich.align import Align
-from rich.console import Console, RenderableType, ConsoleOptions
-from rich.measure import Measurement
-from rich.panel import Panel
-from rich.padding import Padding
-from rich.pretty import Pretty
-from rich.segment import Segment
-from rich.style import Style, StyleType
-from rich.styled import Styled
-from rich.text import Text, TextType
 
-from . import events
+import rich.repr
+from rich.align import Align
+from rich.console import Console, RenderableType
+from rich.padding import Padding
+from rich.style import Style
+from rich.styled import Styled
+from rich.text import Text
+
 from . import errors
+from . import events
 from ._animator import BoundAnimator
-from ._border import Border, BORDER_STYLES
+from ._border import Border
 from ._callback import invoke
+from ._context import active_app
+from ._types import Lines
 from .blank import Blank
 from .dom import DOMNode
-from ._context import active_app
-from .geometry import Size, Spacing, SpacingDimensions
+from .geometry import Size, Spacing
 from .message import Message
 from .messages import Layout, Update
-from .reactive import Reactive, watch
-from ._types import Lines
+from .reactive import watch
 
 if TYPE_CHECKING:
-    from .app import App
     from .view import View
 
 log = getLogger("rich")
diff --git a/src/textual/widgets/_placeholder.py b/src/textual/widgets/_placeholder.py
index a0946b4fc..9fa95bf0d 100644
--- a/src/textual/widgets/_placeholder.py
+++ b/src/textual/widgets/_placeholder.py
@@ -10,7 +10,8 @@ import rich.repr
 from logging import getLogger
 
 from .. import events
-from ..widget import Reactive, Widget
+from ..reactive import Reactive
+from ..widget import Widget
 
 log = getLogger("rich")
 

From 9c2a125c2412c5d011307a80f4552cf9824cc022 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Fri, 21 Jan 2022 13:46:56 +0000
Subject: [PATCH 10/23] Ensuring we get and set Layout as set in view.styles
 everywhere

---
 src/textual/css/_style_properties.py | 29 ++++++------
 src/textual/css/_styles_builder.py   |  3 +-
 src/textual/css/styles.py            | 43 +++++++----------
 src/textual/layouts/factory.py       |  6 ++-
 src/textual/view.py                  | 70 +++++++++++++++-------------
 src/textual/views/_dock_view.py      |  8 ++--
 src/textual/views/_window_view.py    |  8 ++--
 src/textual/widgets/_scroll_view.py  | 12 ++---
 8 files changed, 91 insertions(+), 88 deletions(-)

diff --git a/src/textual/css/_style_properties.py b/src/textual/css/_style_properties.py
index 5b1c11307..3068fbead 100644
--- a/src/textual/css/_style_properties.py
+++ b/src/textual/css/_style_properties.py
@@ -15,6 +15,9 @@ import rich.repr
 from rich.color import Color
 from rich.style import Style
 
+from ._error_tools import friendly_list
+from .constants import NULL_SPACING
+from .errors import StyleTypeError, StyleValueError
 from .scalar import (
     get_symbols,
     UNIT_SYMBOL,
@@ -23,15 +26,14 @@ from .scalar import (
     ScalarOffset,
     ScalarParseError,
 )
-from ..geometry import Spacing, SpacingDimensions
-from .constants import NULL_SPACING
-from .errors import StyleTypeError, StyleValueError
 from .transition import Transition
-from ._error_tools import friendly_list
+from ..geometry import Spacing, SpacingDimensions
 
 if TYPE_CHECKING:
     from .styles import Styles
     from .styles import DockGroup
+    from ..layout import Layout
+    from ..layouts.factory import LayoutName
 
 
 class ScalarProperty:
@@ -80,7 +82,6 @@ class ScalarProperty:
 
 
 class BoxProperty:
-
     DEFAULT = ("", Style())
 
     def __set_name__(self, owner: Styles, name: str) -> None:
@@ -212,7 +213,6 @@ class BorderProperty:
 
 
 class StyleProperty:
-
     DEFAULT_STYLE = Style()
 
     def __set_name__(self, owner: Styles, name: str) -> None:
@@ -291,21 +291,23 @@ class DockProperty:
 
 
 class LayoutProperty:
+    """Descriptor for getting and setting layout."""
+
     def __set_name__(self, owner: Styles, name: str) -> None:
         self._internal_name = f"_rule_{name}"
 
-    def __get__(self, obj: Styles, objtype: type[Styles] | None = None) -> str:
-        return getattr(obj, self._internal_name) or ""
+    def __get__(self, obj: Styles, objtype: type[Styles] | None = None) -> Layout:
+        return getattr(obj, self._internal_name)
 
-    def __set__(self, obj: Styles, layout: str | Styles):
+    def __set__(self, obj: Styles, layout: LayoutName | Layout):
         from ..layouts.factory import get_layout
 
         obj.refresh(True)
-        if isinstance(layout, str):
-            new_layout = get_layout(layout)
-        else:
+        if isinstance(layout, Layout):
             new_layout = layout
-        self._layout = new_layout
+        else:
+            new_layout = get_layout(layout)
+        setattr(obj, self._internal_name, new_layout)
 
 
 class OffsetProperty:
@@ -442,7 +444,6 @@ class ColorProperty:
 
 
 class StyleFlagsProperty:
-
     _VALID_PROPERTIES = {
         "not",
         "bold",
diff --git a/src/textual/css/_styles_builder.py b/src/textual/css/_styles_builder.py
index 17349a04f..ef3a9dba7 100644
--- a/src/textual/css/_styles_builder.py
+++ b/src/textual/css/_styles_builder.py
@@ -18,6 +18,7 @@ from .styles import DockGroup, Styles
 from .types import Edge, Display, Visibility
 from .tokenize import Token
 from .transition import Transition
+from ..layouts.factory import get_layout
 
 
 class StylesBuilder:
@@ -288,7 +289,7 @@ class StylesBuilder:
             if len(tokens) != 1:
                 self.error(name, tokens[0], "unexpected tokens in declaration")
             else:
-                self.styles._rule_layout = tokens[0].value
+                self.styles._rule_layout = get_layout(tokens[0].value)
 
     def process_text(self, name: str, tokens: list[Token], important: bool) -> None:
         style_definition = " ".join(token.value for token in tokens)
diff --git a/src/textual/css/styles.py b/src/textual/css/styles.py
index 09510ae78..18d7eecea 100644
--- a/src/textual/css/styles.py
+++ b/src/textual/css/styles.py
@@ -1,32 +1,14 @@
 from __future__ import annotations
 
+import sys
 from dataclasses import dataclass, field
 from functools import lru_cache
-import sys
 from typing import Any, Iterable, NamedTuple, TYPE_CHECKING
 
-from rich import print
-from rich.color import Color
 import rich.repr
+from rich.color import Color
 from rich.style import Style
 
-from .. import log
-from .._animator import SimpleAnimation, Animation, EasingFunction
-from .._types import MessageTarget
-from .errors import StyleValueError
-from .. import events
-from ._error_tools import friendly_list
-from .types import Specificity3, Specificity4
-from .constants import (
-    VALID_DISPLAY,
-    VALID_VISIBILITY,
-    VALID_LAYOUT,
-    NULL_SPACING,
-)
-from .scalar_animation import ScalarAnimation
-from ..geometry import NULL_OFFSET, Offset, Spacing
-from .scalar import Scalar, ScalarOffset, Unit
-from .transition import Transition
 from ._style_properties import (
     BorderProperty,
     BoxProperty,
@@ -44,16 +26,27 @@ from ._style_properties import (
     TransitionsProperty,
     LayoutProperty,
 )
+from .constants import (
+    VALID_DISPLAY,
+    VALID_VISIBILITY,
+)
+from .scalar import Scalar, ScalarOffset, Unit
+from .scalar_animation import ScalarAnimation
+from .transition import Transition
 from .types import Display, Edge, Visibility
-
+from .types import Specificity3, Specificity4
+from .. import log
+from .._animator import Animation, EasingFunction
+from ..geometry import Spacing
 
 if sys.version_info >= (3, 8):
-    from typing import Literal
+    pass
 else:
-    from typing_extensions import Literal
+    pass
 
 
 if TYPE_CHECKING:
+    from ..layout import Layout
     from ..dom import DOMNode
 
 
@@ -71,7 +64,7 @@ class Styles:
 
     _rule_display: Display | None = None
     _rule_visibility: Visibility | None = None
-    _rule_layout: str | None = None
+    _rule_layout: "Layout" | None = None
 
     _rule_text_color: Color | None = None
     _rule_text_background: Color | None = None
@@ -434,7 +427,7 @@ if __name__ == "__main__":
     styles.dock = "bar"
     styles.layers = "foo bar"
 
-    from rich import inspect, print
+    from rich import print
 
     print(styles.text_style)
     print(styles.text)
diff --git a/src/textual/layouts/factory.py b/src/textual/layouts/factory.py
index fb491e578..5d74a5f9f 100644
--- a/src/textual/layouts/factory.py
+++ b/src/textual/layouts/factory.py
@@ -1,7 +1,11 @@
+from typing import Literal
+
+from ..layout import Layout
 from ..layouts.dock import DockLayout
 from ..layouts.grid import GridLayout
 from ..layouts.vertical import VerticalLayout
 
+LayoutName = Literal["dock", "grid", "vertical"]
 LAYOUT_MAP = {"dock": DockLayout, "grid": GridLayout, "vertical": VerticalLayout}
 
 
@@ -9,7 +13,7 @@ class MissingLayout(Exception):
     pass
 
 
-def get_layout(name: str):
+def get_layout(name: LayoutName) -> Layout:
     """Get a named layout object.
 
     Args:
diff --git a/src/textual/view.py b/src/textual/view.py
index 3d7df4112..f3463fcd0 100644
--- a/src/textual/view.py
+++ b/src/textual/view.py
@@ -1,41 +1,26 @@
 from __future__ import annotations
 
-from itertools import chain
-from typing import Callable, Iterable, ClassVar, TYPE_CHECKING
+from typing import Callable, Iterable
 
-from rich.console import RenderableType
 import rich.repr
+from rich.console import RenderableType
 from rich.style import Style
 
-from . import events
-from . import errors
-from . import log
-from . import messages
-from .layout import Layout, NoWidget, WidgetPlacement
+from . import errors, events, messages
 from .geometry import Size, Offset, Region
+from .layout import Layout, NoWidget, WidgetPlacement
 from .reactive import Reactive, watch
-
 from .widget import Widget
 
 
-if TYPE_CHECKING:
-    from .app import App
-
-
 @rich.repr.auto
 class View(Widget):
-
     STYLES = """
         docks: main=top;
 
     """
 
     def __init__(self, name: str | None = None, id: str | None = None) -> None:
-        # TODO: Get rid of this, replace usages with layout from Styles object
-        from .layouts.dock import DockLayout
-
-        self._layout: Layout = DockLayout()
-
         self.mouse_over: Widget | None = None
         self.widgets: set[Widget] = set()
         self._mouse_style: Style = Style()
@@ -61,9 +46,28 @@ class View(Widget):
     virtual_size = Reactive(Size(0, 0))
 
     async def watch_background(self, value: str) -> None:
-        self._layout.background = value
+        self.layout.background = value
         self.app.refresh()
 
+    @property
+    def layout(self) -> Layout:
+        """Convenience property for accessing ``view.styles.layout``.
+
+        Returns: The Layout associated with this view
+        """
+        return self.styles.layout
+
+    @layout.setter
+    def layout(self, new_value: Layout) -> None:
+        """Convenience property setter for setting ``view.styles.layout``.
+        Args:
+            new_value:
+
+        Returns:
+
+        """
+        self.styles.layout = new_value
+
     @property
     def scroll(self) -> Offset:
         return Offset(self.scroll_x, self.scroll_y)
@@ -89,16 +93,16 @@ class View(Widget):
         return self.app.is_mounted(widget)
 
     def render(self) -> RenderableType:
-        return self._layout
+        return self.layout
 
     def get_offset(self, widget: Widget) -> Offset:
-        return self._layout.get_offset(widget)
+        return self.layout.get_offset(widget)
 
     def get_arrangement(self, size: Size, scroll: Offset) -> Iterable[WidgetPlacement]:
         cached_size, cached_scroll, arrangement = self._cached_arrangement
         if cached_size == size and cached_scroll == scroll:
             return arrangement
-        arrangement = list(self._layout.arrange(self, size, scroll))
+        arrangement = list(self.layout.arrange(self, size, scroll))
         self._cached_arrangement = (size, scroll, arrangement)
         return arrangement
 
@@ -108,7 +112,7 @@ class View(Widget):
             widget = message.widget
             assert isinstance(widget, Widget)
 
-            display_update = self._layout.update_widget(self.console, widget)
+            display_update = self.layout.update_widget(self.console, widget)
             if display_update is not None:
                 self.app.display(display_update)
 
@@ -125,7 +129,7 @@ class View(Widget):
     async def refresh_layout(self) -> None:
         self._cached_arrangement = (Size(), Offset(), [])
         try:
-            await self._layout.mount_all(self)
+            await self.layout.mount_all(self)
             if not self.is_root_view:
                 await self.app.view.refresh_layout()
                 return
@@ -133,8 +137,8 @@ class View(Widget):
             if not self.size:
                 return
 
-            hidden, shown, resized = self._layout.reflow(self, Size(*self.console.size))
-            assert self._layout.map is not None
+            hidden, shown, resized = self.layout.reflow(self, Size(*self.console.size))
+            assert self.layout.map is not None
 
             for widget in hidden:
                 widget.post_message_no_wait(events.Hide(self))
@@ -144,7 +148,7 @@ class View(Widget):
             send_resize = shown
             send_resize.update(resized)
 
-            for widget, region, unclipped_region in self._layout:
+            for widget, region, unclipped_region in self.layout:
                 widget._update_size(unclipped_region.size)
                 if widget in send_resize:
                     widget.post_message_no_wait(
@@ -161,13 +165,13 @@ class View(Widget):
         event.stop()
 
     def get_widget_at(self, x: int, y: int) -> tuple[Widget, Region]:
-        return self._layout.get_widget_at(x, y)
+        return self.layout.get_widget_at(x, y)
 
     def get_style_at(self, x: int, y: int) -> Style:
-        return self._layout.get_style_at(x, y)
+        return self.layout.get_style_at(x, y)
 
     def get_widget_region(self, widget: Widget) -> Region:
-        return self._layout.get_widget_region(widget)
+        return self.layout.get_widget_region(widget)
 
     async def on_mount(self, event: events.Mount) -> None:
         async def watch_background(value: str) -> None:
@@ -176,8 +180,8 @@ class View(Widget):
         watch(self.app, "background", watch_background)
 
     async def on_idle(self, event: events.Idle) -> None:
-        if self._layout.check_update():
-            self._layout.reset_update()
+        if self.layout.check_update():
+            self.layout.reset_update()
             await self.refresh_layout()
 
     async def _on_mouse_move(self, event: events.MouseMove) -> None:
diff --git a/src/textual/views/_dock_view.py b/src/textual/views/_dock_view.py
index 842dae397..22d55c93b 100644
--- a/src/textual/views/_dock_view.py
+++ b/src/textual/views/_dock_view.py
@@ -29,8 +29,8 @@ class DockView(View):
     ) -> None:
 
         dock = Dock(edge, widgets, z)
-        assert isinstance(self._layout, DockLayout)
-        self._layout.docks.append(dock)
+        assert isinstance(self.layout, DockLayout)
+        self.layout.docks.append(dock)
         for widget in widgets:
             if id is not None:
                 widget._id = id
@@ -60,8 +60,8 @@ class DockView(View):
         grid = GridLayout(gap=gap, gutter=gutter, align=align)
         view = View(layout=grid, id=id, name=name)
         dock = Dock(edge, (view,), z)
-        assert isinstance(self._layout, DockLayout)
-        self._layout.docks.append(dock)
+        assert isinstance(self.layout, DockLayout)
+        self.layout.docks.append(dock)
         if size is not do_not_set:
             view.layout_size = cast(Optional[int], size)
         if name is None:
diff --git a/src/textual/views/_window_view.py b/src/textual/views/_window_view.py
index 92edce916..56ee65e63 100644
--- a/src/textual/views/_window_view.py
+++ b/src/textual/views/_window_view.py
@@ -32,7 +32,7 @@ class WindowView(View, layout=VerticalLayout):
         super().__init__(name=name, layout=layout)
 
     async def update(self, widget: Widget | RenderableType) -> None:
-        layout = self._layout
+        layout = self.layout
         assert isinstance(layout, VerticalLayout)
         layout.clear()
         self.widget = widget if isinstance(widget, Widget) else Static(widget)
@@ -46,7 +46,7 @@ class WindowView(View, layout=VerticalLayout):
         await self.emit(WindowChange(self))
 
     async def handle_layout(self, message: messages.Layout) -> None:
-        self._layout.require_update()
+        self.layout.require_update()
         message.stop()
         self.refresh()
 
@@ -54,11 +54,11 @@ class WindowView(View, layout=VerticalLayout):
         await self.emit(WindowChange(self))
 
     async def watch_scroll_x(self, value: int) -> None:
-        self._layout.require_update()
+        self.layout.require_update()
         self.refresh()
 
     async def watch_scroll_y(self, value: int) -> None:
-        self._layout.require_update()
+        self.layout.require_update()
         self.refresh()
 
     async def on_resize(self, event: events.Resize) -> None:
diff --git a/src/textual/widgets/_scroll_view.py b/src/textual/widgets/_scroll_view.py
index 210edf740..fd53c1203 100644
--- a/src/textual/widgets/_scroll_view.py
+++ b/src/textual/widgets/_scroll_view.py
@@ -93,13 +93,13 @@ class ScrollView(View):
         await self.window.update(renderable)
 
     async def on_mount(self, event: events.Mount) -> None:
-        assert isinstance(self._layout, GridLayout)
-        self._layout.place(
+        assert isinstance(self.layout, GridLayout)
+        self.layout.place(
             content=self.window,
             vscroll=self.vscroll,
             hscroll=self.hscroll,
         )
-        await self._layout.mount_all(self)
+        await self.layout.mount_all(self)
 
     def home(self) -> None:
         self.x = self.y = 0
@@ -215,10 +215,10 @@ class ScrollView(View):
         self.vscroll.virtual_size = virtual_height
         self.vscroll.window_size = height
 
-        assert isinstance(self._layout, GridLayout)
+        assert isinstance(self.layout, GridLayout)
 
-        vscroll_change = self._layout.show_column("vscroll", virtual_height > height)
-        hscroll_change = self._layout.show_row("hscroll", virtual_width > width)
+        vscroll_change = self.layout.show_column("vscroll", virtual_height > height)
+        hscroll_change = self.layout.show_row("hscroll", virtual_width > width)
         if hscroll_change or vscroll_change:
             self.refresh(layout=True)
 

From d04c66291b3a1e90226b8717f35a83b57bf751b3 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Fri, 21 Jan 2022 14:14:40 +0000
Subject: [PATCH 11/23] Improve error message when layout doesnt exist, add
 tests for parsing layout from CSS

---
 src/textual/css/_styles_builder.py | 25 +++++++++++++++++--------
 src/textual/layouts/factory.py     |  2 +-
 tests/test_css_parse.py            | 21 +++++++++++++++++++++
 3 files changed, 39 insertions(+), 9 deletions(-)

diff --git a/src/textual/css/_styles_builder.py b/src/textual/css/_styles_builder.py
index ef3a9dba7..8a826507a 100644
--- a/src/textual/css/_styles_builder.py
+++ b/src/textual/css/_styles_builder.py
@@ -6,19 +6,19 @@ import rich.repr
 from rich.color import Color
 from rich.style import Style
 
+from ._error_tools import friendly_list
 from .constants import VALID_BORDER, VALID_EDGE, VALID_DISPLAY, VALID_VISIBILITY
 from .errors import DeclarationError
-from ._error_tools import friendly_list
-from .._duration import _duration_as_seconds
-from .._easing import EASING
-from ..geometry import Spacing, SpacingDimensions
 from .model import Declaration
 from .scalar import Scalar, ScalarOffset, Unit, ScalarError
 from .styles import DockGroup, Styles
-from .types import Edge, Display, Visibility
 from .tokenize import Token
 from .transition import Transition
-from ..layouts.factory import get_layout
+from .types import Edge, Display, Visibility
+from .._duration import _duration_as_seconds
+from .._easing import EASING
+from ..geometry import Spacing, SpacingDimensions
+from ..layouts.factory import get_layout, LayoutName, MissingLayout, LAYOUT_MAP
 
 
 class StylesBuilder:
@@ -60,7 +60,7 @@ class StylesBuilder:
                 self.styles.important.add(rule_name)
             try:
                 process_method(declaration.name, tokens, important)
-            except DeclarationError as error:
+            except DeclarationError:
                 raise
             except Exception as error:
                 self.error(declaration.name, declaration.token, str(error))
@@ -289,7 +289,16 @@ class StylesBuilder:
             if len(tokens) != 1:
                 self.error(name, tokens[0], "unexpected tokens in declaration")
             else:
-                self.styles._rule_layout = get_layout(tokens[0].value)
+                value = tokens[0].value
+                layout_name = cast(LayoutName, value)
+                try:
+                    self.styles._rule_layout = get_layout(layout_name)
+                except MissingLayout:
+                    self.error(
+                        name,
+                        tokens[0],
+                        f"invalid value for layout (received {value!r}, expected {friendly_list(LAYOUT_MAP.keys())})",
+                    )
 
     def process_text(self, name: str, tokens: list[Token], important: bool) -> None:
         style_definition = " ".join(token.value for token in tokens)
diff --git a/src/textual/layouts/factory.py b/src/textual/layouts/factory.py
index 5d74a5f9f..03776cdee 100644
--- a/src/textual/layouts/factory.py
+++ b/src/textual/layouts/factory.py
@@ -28,5 +28,5 @@ def get_layout(name: LayoutName) -> Layout:
 
     layout_class = LAYOUT_MAP.get(name)
     if layout_class is None:
-        raise MissingLayout("no layout called {name!r}")
+        raise MissingLayout(f"no layout called {name!r}, valid layouts")
     return layout_class()
diff --git a/tests/test_css_parse.py b/tests/test_css_parse.py
index f17a0c3e9..ad03fb34d 100644
--- a/tests/test_css_parse.py
+++ b/tests/test_css_parse.py
@@ -4,6 +4,27 @@ from rich.color import Color, ColorType
 from textual.css.scalar import Scalar, Unit
 from textual.css.stylesheet import Stylesheet, StylesheetParseError
 from textual.css.transition import Transition
+from textual.layouts.dock import DockLayout
+
+
+class TestParseLayout:
+    def test_valid_layout_name(self):
+        css = "#some-widget { layout: dock; }"
+
+        stylesheet = Stylesheet()
+        stylesheet.parse(css)
+
+        styles = stylesheet.rules[0].styles
+        assert isinstance(styles.layout, DockLayout)
+
+    def test_invalid_layout_name(self):
+        css = "#some-widget { layout: invalidlayout; }"
+
+        stylesheet = Stylesheet()
+        with pytest.raises(StylesheetParseError) as ex:
+            stylesheet.parse(css)
+
+        assert ex.value.errors is not None
 
 
 class TestParseText:

From 742104eb2189d4772b6d0996a44ba68c9ae1a5c4 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Fri, 21 Jan 2022 14:15:09 +0000
Subject: [PATCH 12/23] Remove _layout attribute from `App`

---
 src/textual/app.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/textual/app.py b/src/textual/app.py
index afdb99892..8708bf5ab 100644
--- a/src/textual/app.py
+++ b/src/textual/app.py
@@ -90,7 +90,6 @@ class App(DOMNode):
         self._screen = screen
         self.driver_class = driver_class or LinuxDriver
         self._title = title
-        self._layout = DockLayout()
         self._view_stack: list[View] = []
 
         self.focused: Widget | None = None

From 8601cea0faf7bc4cb8cf25987ad466b2d80f4dd6 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Fri, 21 Jan 2022 14:16:52 +0000
Subject: [PATCH 13/23] Remove redundant block of code

---
 src/textual/css/styles.py | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/src/textual/css/styles.py b/src/textual/css/styles.py
index 18d7eecea..db374dabf 100644
--- a/src/textual/css/styles.py
+++ b/src/textual/css/styles.py
@@ -39,11 +39,6 @@ from .. import log
 from .._animator import Animation, EasingFunction
 from ..geometry import Spacing
 
-if sys.version_info >= (3, 8):
-    pass
-else:
-    pass
-
 
 if TYPE_CHECKING:
     from ..layout import Layout

From 1bc4bf54ae44350fce0144615636d639064c950d Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Fri, 21 Jan 2022 14:27:47 +0000
Subject: [PATCH 14/23] Adding tests for layout factory

---
 tests/layouts/test_factory.py | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
 create mode 100644 tests/layouts/test_factory.py

diff --git a/tests/layouts/test_factory.py b/tests/layouts/test_factory.py
new file mode 100644
index 000000000..7505902f9
--- /dev/null
+++ b/tests/layouts/test_factory.py
@@ -0,0 +1,14 @@
+import pytest
+
+from textual.layouts.dock import DockLayout
+from textual.layouts.factory import get_layout, MissingLayout
+
+
+def test_get_layout_valid_layout():
+    layout_class = get_layout("dock")
+    assert type(layout_class) is DockLayout
+
+
+def test_get_layout_invalid_layout():
+    with pytest.raises(MissingLayout):
+        get_layout("invalid")

From 837144cc13b36161ab4d05918a93d3eb451af25d Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Fri, 21 Jan 2022 14:28:37 +0000
Subject: [PATCH 15/23] Remove a `log`

---
 src/textual/css/stylesheet.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/textual/css/stylesheet.py b/src/textual/css/stylesheet.py
index 802c86fbb..58c73fee3 100644
--- a/src/textual/css/stylesheet.py
+++ b/src/textual/css/stylesheet.py
@@ -140,7 +140,6 @@ class Stylesheet:
             for name, specificity_rules in rule_attributes.items()
         ]
 
-        log(node.id, node_rules)
         node.styles.apply_rules(node_rules)
 
     def update(self, root: DOMNode) -> None:

From e6919ac35bc376e0b400975a8a6f5704036deb40 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Fri, 21 Jan 2022 14:36:48 +0000
Subject: [PATCH 16/23] Add docstring to Stylesheet.apply

---
 src/textual/css/stylesheet.py | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/textual/css/stylesheet.py b/src/textual/css/stylesheet.py
index 58c73fee3..616bcf1b2 100644
--- a/src/textual/css/stylesheet.py
+++ b/src/textual/css/stylesheet.py
@@ -108,6 +108,18 @@ class Stylesheet:
                 yield selector_set.specificity
 
     def apply(self, node: DOMNode) -> None:
+        """
+        Args:
+            node (DOMNode): The ``DOMNode`` to apply the stylesheet to.
+                Applies the styles defined in this ``Stylesheet`` to the node.
+                If the same rule is defined multiple times for the node (e.g. multiple
+                classes modifying the same CSS property), then only the most specific
+                rule will be applied.
+
+        Returns:
+            None
+        """
+
         # Dictionary of rule attribute names e.g. "text_background" to list of tuples.
         # The tuples contain the rule specificity, and the value for that rule.
         # We can use this to determine, for a given rule, whether we should apply it

From 60134b650d42d46313804b2595778e27fe4575a2 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Fri, 21 Jan 2022 14:39:20 +0000
Subject: [PATCH 17/23] Rename variable in a test

---
 tests/layouts/test_factory.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/layouts/test_factory.py b/tests/layouts/test_factory.py
index 7505902f9..8935556a5 100644
--- a/tests/layouts/test_factory.py
+++ b/tests/layouts/test_factory.py
@@ -5,8 +5,8 @@ from textual.layouts.factory import get_layout, MissingLayout
 
 
 def test_get_layout_valid_layout():
-    layout_class = get_layout("dock")
-    assert type(layout_class) is DockLayout
+    layout = get_layout("dock")
+    assert type(layout) is DockLayout
 
 
 def test_get_layout_invalid_layout():

From deb7f1cb54bba2dc4d7b32215aef560bf004ae3d Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Fri, 21 Jan 2022 15:25:15 +0000
Subject: [PATCH 18/23] Use dock layout by default in View node-level CSS

---
 examples/basic.css                   |  1 -
 src/textual/css/_style_properties.py | 15 ++++++++++++++-
 src/textual/view.py                  |  2 +-
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/examples/basic.css b/examples/basic.css
index 279f6e520..efafe797e 100644
--- a/examples/basic.css
+++ b/examples/basic.css
@@ -1,7 +1,6 @@
 /* CSS file for basic.py */
 
 App > View {
-  layout: dock;
   docks: side=left/1;
   text: on #20639b;
 }
diff --git a/src/textual/css/_style_properties.py b/src/textual/css/_style_properties.py
index 3068fbead..4496923f2 100644
--- a/src/textual/css/_style_properties.py
+++ b/src/textual/css/_style_properties.py
@@ -297,10 +297,23 @@ class LayoutProperty:
         self._internal_name = f"_rule_{name}"
 
     def __get__(self, obj: Styles, objtype: type[Styles] | None = None) -> Layout:
+        """
+        Args:
+            obj (Styles): The Styles object
+            objtype (type[Styles]): The Styles class
+        Returns:
+            The ``Layout`` object.
+        """
         return getattr(obj, self._internal_name)
 
     def __set__(self, obj: Styles, layout: LayoutName | Layout):
-        from ..layouts.factory import get_layout
+        """
+        Args:
+            obj (Styles): The Styles object.
+            layout (LayoutName | Layout): The layout to use. You can supply a ``LayoutName``
+                (a string literal such as ``"dock"``) or a ``Layout`` object.
+        """
+        from ..layouts.factory import get_layout  # Prevents circular import
 
         obj.refresh(True)
         if isinstance(layout, Layout):
diff --git a/src/textual/view.py b/src/textual/view.py
index f3463fcd0..9617fc251 100644
--- a/src/textual/view.py
+++ b/src/textual/view.py
@@ -16,8 +16,8 @@ from .widget import Widget
 @rich.repr.auto
 class View(Widget):
     STYLES = """
+        layout: dock;
         docks: main=top;
-
     """
 
     def __init__(self, name: str | None = None, id: str | None = None) -> None:

From 5690f946d1c5e00c4a54842ca988a5808b01a533 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Fri, 21 Jan 2022 15:50:58 +0000
Subject: [PATCH 19/23] Testing to ensure layout can properly be set via view

---
 src/textual/css/_style_properties.py |  4 ++--
 tests/test_view.py                   | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)
 create mode 100644 tests/test_view.py

diff --git a/src/textual/css/_style_properties.py b/src/textual/css/_style_properties.py
index 4496923f2..12c9075f7 100644
--- a/src/textual/css/_style_properties.py
+++ b/src/textual/css/_style_properties.py
@@ -30,9 +30,9 @@ from .transition import Transition
 from ..geometry import Spacing, SpacingDimensions
 
 if TYPE_CHECKING:
+    from ..layout import Layout
     from .styles import Styles
     from .styles import DockGroup
-    from ..layout import Layout
     from ..layouts.factory import LayoutName
 
 
@@ -313,7 +313,7 @@ class LayoutProperty:
             layout (LayoutName | Layout): The layout to use. You can supply a ``LayoutName``
                 (a string literal such as ``"dock"``) or a ``Layout`` object.
         """
-        from ..layouts.factory import get_layout  # Prevents circular import
+        from ..layouts.factory import get_layout, Layout  # Prevents circular import
 
         obj.refresh(True)
         if isinstance(layout, Layout):
diff --git a/tests/test_view.py b/tests/test_view.py
new file mode 100644
index 000000000..08db68d69
--- /dev/null
+++ b/tests/test_view.py
@@ -0,0 +1,18 @@
+import pytest
+
+from textual.layouts.dock import DockLayout
+from textual.layouts.grid import GridLayout
+from textual.layouts.vertical import VerticalLayout
+from textual.view import View
+
+
+@pytest.mark.parametrize("layout_name, layout_type", [
+    ["dock", DockLayout],
+    ["grid", GridLayout],
+    ["vertical", VerticalLayout],
+])
+def test_view_layout_get_and_set(layout_name, layout_type):
+    view = View()
+    view.layout = layout_name
+    assert type(view.layout) is layout_type
+    assert view.styles.layout is view.layout

From a8cd64964f098277cb3346b9d7e3514e608ec7ac Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Fri, 21 Jan 2022 15:54:13 +0000
Subject: [PATCH 20/23] Fix a docstring

---
 src/textual/view.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/textual/view.py b/src/textual/view.py
index 9617fc251..b16645f10 100644
--- a/src/textual/view.py
+++ b/src/textual/view.py
@@ -64,7 +64,7 @@ class View(Widget):
             new_value:
 
         Returns:
-
+            None
         """
         self.styles.layout = new_value
 

From 89524e301ebdf1b4dca482caafe479739d2df632 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Fri, 21 Jan 2022 16:00:47 +0000
Subject: [PATCH 21/23] Remove some unused logging

---
 src/textual/css/styles.py | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/src/textual/css/styles.py b/src/textual/css/styles.py
index db374dabf..51d6035cb 100644
--- a/src/textual/css/styles.py
+++ b/src/textual/css/styles.py
@@ -269,9 +269,6 @@ class Styles:
                 else:
                     setattr(styles, f"_rule_{key}", value)
 
-        if self.node.id == "_root":
-            log("_root.styles.layout =", self.node.styles.layout)
-
         if self.node is not None:
             self.node.on_style_change()
 

From cea331ef4d8ff56a0e358056f1bf8dc01a1f4199 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Fri, 21 Jan 2022 16:04:29 +0000
Subject: [PATCH 22/23] Ensure Python 3.7 support using typing_extensions

---
 src/textual/layouts/factory.py | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/textual/layouts/factory.py b/src/textual/layouts/factory.py
index 03776cdee..4953fb50a 100644
--- a/src/textual/layouts/factory.py
+++ b/src/textual/layouts/factory.py
@@ -1,10 +1,15 @@
-from typing import Literal
+import sys
 
 from ..layout import Layout
 from ..layouts.dock import DockLayout
 from ..layouts.grid import GridLayout
 from ..layouts.vertical import VerticalLayout
 
+if sys.version_info >= (3, 8):
+    from typing import Literal
+else:
+    from typing_extensions import Literal
+
 LayoutName = Literal["dock", "grid", "vertical"]
 LAYOUT_MAP = {"dock": DockLayout, "grid": GridLayout, "vertical": VerticalLayout}
 

From 8c3bc4135ec58ccac19ead529ea563d1f2583665 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Tue, 25 Jan 2022 14:20:32 +0000
Subject: [PATCH 23/23] Add missing docstring, use explicit kwargs, remove
 id=_root

---
 src/textual/app.py                   |  2 +-
 src/textual/css/_style_properties.py | 14 +++++++-------
 src/textual/css/stylesheet.py        |  3 ++-
 3 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/src/textual/app.py b/src/textual/app.py
index 8708bf5ab..96ca521e4 100644
--- a/src/textual/app.py
+++ b/src/textual/app.py
@@ -503,7 +503,7 @@ class App(DOMNode):
         # Handle input events that haven't been forwarded
         # If the event has been forwarded it may have bubbled up back to the App
         if isinstance(event, events.Mount):
-            view = View(id="_root")
+            view = View()
             self.register(self, view)
             await self.push_view(view)
             await super().on_event(event)
diff --git a/src/textual/css/_style_properties.py b/src/textual/css/_style_properties.py
index 12c9075f7..ff673fa10 100644
--- a/src/textual/css/_style_properties.py
+++ b/src/textual/css/_style_properties.py
@@ -257,7 +257,7 @@ class SpacingProperty:
         return getattr(obj, self._internal_name) or NULL_SPACING
 
     def __set__(self, obj: Styles, spacing: SpacingDimensions) -> Spacing:
-        obj.refresh(True)
+        obj.refresh(layout=True)
         spacing = Spacing.unpack(spacing)
         setattr(obj, self._internal_name, spacing)
         return spacing
@@ -272,7 +272,7 @@ class DocksProperty:
     def __set__(
         self, obj: Styles, docks: Iterable[DockGroup] | None
     ) -> Iterable[DockGroup] | None:
-        obj.refresh(True)
+        obj.refresh(layout=True)
         if docks is None:
             obj._rule_docks = None
         else:
@@ -285,7 +285,7 @@ class DockProperty:
         return obj._rule_dock or ""
 
     def __set__(self, obj: Styles, spacing: str | None) -> str | None:
-        obj.refresh(True)
+        obj.refresh(layout=True)
         obj._rule_dock = spacing
         return spacing
 
@@ -315,7 +315,7 @@ class LayoutProperty:
         """
         from ..layouts.factory import get_layout, Layout  # Prevents circular import
 
-        obj.refresh(True)
+        obj.refresh(layout=True)
         if isinstance(layout, Layout):
             new_layout = layout
         else:
@@ -335,7 +335,7 @@ class OffsetProperty:
     def __set__(
         self, obj: Styles, offset: tuple[int | str, int | str] | ScalarOffset
     ) -> tuple[int | str, int | str] | ScalarOffset:
-        obj.refresh(True)
+        obj.refresh(layout=True)
         if isinstance(offset, ScalarOffset):
             setattr(obj, self._internal_name, offset)
             return offset
@@ -403,7 +403,7 @@ class NameProperty:
         return getattr(obj, self._internal_name) or ""
 
     def __set__(self, obj: Styles, name: str | None) -> str | None:
-        obj.refresh(True)
+        obj.refresh(layout=True)
         if not isinstance(name, str):
             raise StyleTypeError(f"{self._name} must be a str")
         setattr(obj, self._internal_name, name)
@@ -423,7 +423,7 @@ class NameListProperty:
     def __set__(
         self, obj: Styles, names: str | tuple[str] | None = None
     ) -> str | tuple[str] | None:
-        obj.refresh(True)
+        obj.refresh(layout=True)
         names_value: tuple[str, ...] | None = None
         if isinstance(names, str):
             names_value = tuple(name.strip().lower() for name in names.split(" "))
diff --git a/src/textual/css/stylesheet.py b/src/textual/css/stylesheet.py
index 616bcf1b2..8c6075011 100644
--- a/src/textual/css/stylesheet.py
+++ b/src/textual/css/stylesheet.py
@@ -108,7 +108,8 @@ class Stylesheet:
                 yield selector_set.specificity
 
     def apply(self, node: DOMNode) -> None:
-        """
+        """Apply the stylesheet to a DOM node.
+
         Args:
             node (DOMNode): The ``DOMNode`` to apply the stylesheet to.
                 Applies the styles defined in this ``Stylesheet`` to the node.