From d45b0448880f915e0c7dc569162fff1569be33a9 Mon Sep 17 00:00:00 2001
From: Will McGugan <willmcgugan@gmail.com>
Date: Fri, 27 May 2022 15:17:16 +0100
Subject: [PATCH] simplify

---
 src/textual/_ansi_sequences.py |  8 +++-----
 src/textual/_compositor.py     | 11 +++++++----
 src/textual/app.py             | 18 ++++++++++--------
 src/textual/screen.py          |  1 -
 4 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/src/textual/_ansi_sequences.py b/src/textual/_ansi_sequences.py
index a738ed7c4..61614ca65 100644
--- a/src/textual/_ansi_sequences.py
+++ b/src/textual/_ansi_sequences.py
@@ -300,8 +300,6 @@ ANSI_SEQUENCES_KEYS: Mapping[str, Tuple[Keys, ...]] = {
     "\x1b[1;8y": (Keys.Escape, Keys.ControlShift9),
 }
 
-
-TERMINAL_MODES_ANSI_SEQUENCES: Mapping[str, str] = {
-    "sync_start": "\x1b[?2026h",
-    "sync_stop": "\x1b[?2026l",
-}
+# https://gist.github.com/christianparpart/d8a62cc1ab659194337d73e399004036
+SYNC_START = "\x1b[?2026h"
+SYNC_END = "\x1b[?2026l"
diff --git a/src/textual/_compositor.py b/src/textual/_compositor.py
index 392a463ce..8b3b270cb 100644
--- a/src/textual/_compositor.py
+++ b/src/textual/_compositor.py
@@ -254,12 +254,15 @@ class Compositor:
         if screen not in self._dirty_regions:
             crop_screen = screen.intersection
             changes = map.items() ^ old_map.items()
-            self._dirty_regions.update(
-                [
+            regions = {
+                region
+                for region in (
                     crop_screen(map_geometry.visible_region)
                     for _, map_geometry in changes
-                ]
-            )
+                )
+                if region
+            }
+            self._dirty_regions.update(regions)
 
         return ReflowResult(
             hidden=hidden_widgets,
diff --git a/src/textual/app.py b/src/textual/app.py
index eab58f0f5..c73ecd525 100644
--- a/src/textual/app.py
+++ b/src/textual/app.py
@@ -22,7 +22,7 @@ from typing import (
     TYPE_CHECKING,
 )
 
-from ._ansi_sequences import TERMINAL_MODES_ANSI_SEQUENCES
+from ._ansi_sequences import SYNC_START, SYNC_END
 
 if sys.version_info >= (3, 8):
     from typing import Literal
@@ -897,10 +897,12 @@ class App(Generic[ReturnType], DOMNode):
             console = self.console
             self._begin_update()
             try:
-                console.print(renderable)
-            except Exception as error:
-                self.on_exception(error)
-            self._end_update()
+                try:
+                    console.print(renderable)
+                except Exception as error:
+                    self.on_exception(error)
+            finally:
+                self._end_update()
             console.file.flush()
 
     def measure(self, renderable: RenderableType, max_width=100_000) -> int:
@@ -1103,16 +1105,16 @@ class App(Generic[ReturnType], DOMNode):
     def handle_terminal_supports_synchronized_output(
         self, message: messages.TerminalSupportsSynchronizedOutput
     ) -> None:
-        log("SynchronizedOutput mode is supported by this terminal")
+        log("[b green]SynchronizedOutput mode is supported")
         self._sync_available = True
 
     def _begin_update(self) -> None:
         if self._sync_available:
-            self.console.file.write(TERMINAL_MODES_ANSI_SEQUENCES["sync_start"])
+            self.console.file.write(SYNC_START)
 
     def _end_update(self) -> None:
         if self._sync_available:
-            self.console.file.write(TERMINAL_MODES_ANSI_SEQUENCES["sync_stop"])
+            self.console.file.write(SYNC_END)
 
 
 _uvloop_init_done: bool = False
diff --git a/src/textual/screen.py b/src/textual/screen.py
index 7b7887c06..e19b4b470 100644
--- a/src/textual/screen.py
+++ b/src/textual/screen.py
@@ -9,7 +9,6 @@ from rich.style import Style
 
 from . import events, messages, errors
 
-from .color import Color
 from .geometry import Offset, Region, Size
 from ._compositor import Compositor, MapGeometry
 from .reactive import Reactive