Make scrollable containers focusable. (#2317)

* Make scrollable containers focusable.

Related issues: #2270.

Author: rodrigogiraoserrao

CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - A clicked tab will now be scrolled to the center of its tab container https://github.com/Textualize/textual/pull/2276
 - Style updates are now done immediately rather than on_idle https://github.com/Textualize/textual/pull/2304
 - `ButtonVariant` is now exported from `textual.widgets.button` https://github.com/Textualize/textual/issues/2264
+- `HorizontalScroll` and `VerticalScroll` are now focusable by default https://github.com/Textualize/textual/pull/2317
 
 ### Added
 

src/textual/containers.py

@@ -31,7 +31,7 @@ class Vertical(Widget):
     """
 
 
-class VerticalScroll(Widget):
+class VerticalScroll(Widget, can_focus=True):
     """A container which arranges children vertically, with an automatic vertical scrollbar."""
 
     DEFAULT_CSS = """
@@ -55,7 +55,7 @@ class Horizontal(Widget):
     """
 
 
-class HorizontalScroll(Widget):
+class HorizontalScroll(Widget, can_focus=True):
     """A container which arranges children horizontally, with an automatic horizontal scrollbar."""
 
     DEFAULT_CSS = """

tests/snapshot_tests/test_snapshots.py

@@ -87,7 +87,7 @@ def test_input_and_focus(snap_compare):
 
 def test_buttons_render(snap_compare):
     # Testing button rendering. We press tab to focus the first button too.
-    assert snap_compare(WIDGET_EXAMPLES_DIR / "button.py", press=["tab"])
+    assert snap_compare(WIDGET_EXAMPLES_DIR / "button.py", press=["tab", "tab"])
 
 
 def test_placeholder_render(snap_compare):
@@ -269,7 +269,7 @@ def test_programmatic_scrollbar_gutter_change(snap_compare):
 
 
 def test_borders_preview(snap_compare):
-    assert snap_compare(CLI_PREVIEWS_DIR / "borders.py", press=["tab", "enter"])
+    assert snap_compare(CLI_PREVIEWS_DIR / "borders.py", press=["tab", "tab", "enter"])
 
 
 def test_colors_preview(snap_compare):
@@ -325,7 +325,9 @@ def test_disabled_widgets(snap_compare):
 
 
 def test_focus_component_class(snap_compare):
-    assert snap_compare(SNAPSHOT_APPS_DIR / "focus_component_class.py", press=["tab"])
+    assert snap_compare(
+        SNAPSHOT_APPS_DIR / "focus_component_class.py", press=["tab", "tab"]
+    )
 
 
 def test_line_api_scrollbars(snap_compare):