Avoid docks when scrolling (#2571)

* handle docked layers

* handle scroll better

* snapshot update

* remove commented out code

* superflous

* dock gutter

* snapshit

* snapshit test

* changelog

* mistake

* docstrings

* changelog

* whitespace

* missing punctuation

* ofx docstring

* Apply suggestions from code review

Co-authored-by: Rodrigo Girão Serrão <5621605+rodrigogiraoserrao@users.noreply.github.com>

---------

Co-authored-by: Rodrigo Girão Serrão <5621605+rodrigogiraoserrao@users.noreply.github.com>

tests/snapshot_tests/snapshot_apps/dock_scroll2.py

@@ -0,0 +1,33 @@
+from textual.app import App
+from textual.widgets import Header, Label, Footer
+
+
+# Same as dock_scroll.py but with 2 labels
+class TestApp(App):
+    BINDINGS = [("ctrl+q", "app.quit", "Quit")]
+    CSS = """
+    
+    Label {
+        border: solid red;
+    }
+    Footer {
+        height: 4;
+    }
+    """
+
+    def compose(self):
+        text = (
+            "this is a sample sentence and here are some words".replace(" ", "\n") * 2
+        )
+        yield Header()
+        yield Label(text)
+        yield Label(text)
+        yield Footer()
+
+    def on_mount(self):
+        self.dark = False
+
+
+if __name__ == "__main__":
+    app = TestApp()
+    app.run()

tests/snapshot_tests/snapshot_apps/dock_scroll_off_by_one.py

@@ -0,0 +1,17 @@
+from textual.app import App, ComposeResult
+from textual.widgets import Checkbox, Footer
+
+
+class ScrollOffByOne(App):
+    def compose(self) -> ComposeResult:
+        for number in range(1, 100):
+            yield Checkbox(str(number))
+        yield Footer()
+
+    def on_mount(self) -> None:
+        self.query_one("Screen").scroll_end()
+
+
+app = ScrollOffByOne()
+if __name__ == "__main__":
+    app.run()

tests/snapshot_tests/snapshot_apps/horizontal_auto_width.css

@@ -19,6 +19,6 @@
 
 #horizontal {
     width: auto;
-    height: auto;
+    height: 4;
     background: darkslateblue;
-}
+}

tests/snapshot_tests/snapshot_apps/scroll_to.py

@@ -0,0 +1,19 @@
+from textual.app import App, ComposeResult
+from textual.widgets import Checkbox, Footer
+
+
+class ScrollOffByOne(App):
+    """Scroll to item 50."""
+
+    def compose(self) -> ComposeResult:
+        for number in range(1, 100):
+            yield Checkbox(str(number), id=f"number-{number}")
+        yield Footer()
+
+    def on_ready(self) -> None:
+        self.query_one("#number-50").scroll_visible()
+
+
+app = ScrollOffByOne()
+if __name__ == "__main__":
+    app.run()