From c667c861071b094c50ecb0025babc518a36ec529 Mon Sep 17 00:00:00 2001
From: Will McGugan <willmcgugan@gmail.com>
Date: Tue, 7 Nov 2023 16:22:40 +0000
Subject: [PATCH] Blur (#3645)

* added blur

* add blur pseudo class

* added blur psuedo class

* added test
---
 CHANGELOG.md          |  1 +
 docs/guide/CSS.md     |  1 +
 src/textual/widget.py |  2 ++
 tests/test_app.py     | 15 +++++++++++++--
 tests/test_focus.py   | 30 +++++++++++++++++++++++++++++-
 5 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 43b32ed2b1..4b04363b78 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Fixed
 
 - Duplicate CSS errors when parsing CSS from a screen https://github.com/Textualize/textual/issues/3581
+- Added missing `blur` pseudo class https://github.com/Textualize/textual/issues/3439
 - Fixed visual glitched characters on Windows due to Python limitation https://github.com/Textualize/textual/issues/2548
 
 ### Changed
diff --git a/docs/guide/CSS.md b/docs/guide/CSS.md
index 7365f0b094..9dd18155f1 100644
--- a/docs/guide/CSS.md
+++ b/docs/guide/CSS.md
@@ -324,6 +324,7 @@ Here are some other pseudo classes:
 - `:disabled` Matches widgets which are in a disabled state.
 - `:enabled` Matches widgets which are in an enabled state.
 - `:focus` Matches widgets which have input focus.
+- `:blur` Matches widgets which *do not* have input focus.
 - `:focus-within` Matches widgets with a focused child widget.
 - `:dark` Matches widgets in dark mode (where `App.dark == True`).
 - `:light` Matches widgets in dark mode (where `App.dark == False`).
diff --git a/src/textual/widget.py b/src/textual/widget.py
index 005fdf14d2..2d4dcd3ec9 100644
--- a/src/textual/widget.py
+++ b/src/textual/widget.py
@@ -2779,6 +2779,8 @@ def get_pseudo_classes(self) -> Iterable[str]:
             yield "hover"
         if self.has_focus:
             yield "focus"
+        else:
+            yield "blur"
         if self.can_focus:
             yield "can-focus"
         try:
diff --git a/tests/test_app.py b/tests/test_app.py
index 1fe20a46a4..e5afed1e2a 100644
--- a/tests/test_app.py
+++ b/tests/test_app.py
@@ -30,14 +30,25 @@ async def test_hover_update_styles():
     app = MyApp()
     async with app.run_test() as pilot:
         button = app.query_one(Button)
-        assert button.pseudo_classes == {"enabled", "can-focus", "dark"}
+        assert button.pseudo_classes == {
+            "blur",
+            "can-focus",
+            "dark",
+            "enabled",
+        }
 
         # Take note of the initial background colour
         initial_background = button.styles.background
         await pilot.hover(Button)
 
         # We've hovered, so ensure the pseudoclass is present and background changed
-        assert button.pseudo_classes == {"enabled", "hover", "can-focus", "dark"}
+        assert button.pseudo_classes == {
+            "blur",
+            "can-focus",
+            "dark",
+            "enabled",
+            "hover",
+        }
         assert button.styles.background != initial_background
 
 
diff --git a/tests/test_focus.py b/tests/test_focus.py
index 489d808c26..486356bfe0 100644
--- a/tests/test_focus.py
+++ b/tests/test_focus.py
@@ -1,6 +1,6 @@
 import pytest
 
-from textual.app import App
+from textual.app import App, ComposeResult
 from textual.containers import Container
 from textual.screen import Screen
 from textual.widget import Widget
@@ -309,3 +309,31 @@ def compose(self):
             w11,
             w12,
         ]
+
+
+async def test_focus_pseudo_class():
+    """Test focus and blue pseudo classes"""
+
+    # https://github.com/Textualize/textual/pull/3645
+    class FocusApp(App):
+        AUTO_FOCUS = None
+
+        def compose(self) -> ComposeResult:
+            yield Button("Hello")
+
+    app = FocusApp()
+    async with app.run_test() as pilot:
+        button = app.query_one(Button)
+        classes = list(button.get_pseudo_classes())
+        # Blurred, not focused
+        assert "blur" in classes
+        assert "focus" not in classes
+
+        # Focus the button
+        button.focus()
+        await pilot.pause()
+
+        # Focused, not blurred
+        classes = list(button.get_pseudo_classes())
+        assert "blur" not in classes
+        assert "focus" in classes