Hide the selected-tab overline in unfocused windows [patch]

ThemeProvider.ImGui/ImGuiPaletteMapper.cs

@@ -128,6 +128,9 @@ public IReadOnlyDictionary<ImGuiCol, Vector4> MapTheme(ISemanticTheme theme)
 			// Striped rows hold input frames, which are drawn in FrameBg with no border by default. A
 			// translucent stripe lands between the row and frame colors, so a frame in an odd row stays visible.
 			{ ImGuiCol.TableRowBgAlt, 0.50f },
+			// The overline marks the focused window's selected tab, so an unfocused window's selected tab
+			// draws none, as in ImGui's stock styles. Drawing it in both made every dock node look focused.
+			{ ImGuiCol.TabDimmedSelectedOverline, 0f },
 		};
 
 		// Convert the semantic colors to ImGui Vector4 format

ThemeProvider.Test/ImGuiPaletteMapperTests.cs

@@ -254,6 +254,26 @@ public void MapTheme_SelectedTabsDifferFromTheirTabBar()
 		}
 	}
 
+	/// <summary>
+	/// ImGui draws TabSelectedOverline on the focused window's selected tab and TabDimmedSelectedOverline on
+	/// every unfocused one's. The overline is the cue for which window has focus, so only the focused one may
+	/// show it: the dimmed overline is transparent, as in ImGui's stock styles.
+	/// </summary>
+	[TestMethod]
+	public void MapTheme_OnlyTheFocusedSelectedTabHasAnOverline()
+	{
+		ImGuiPaletteMapper mapper = new();
+
+		foreach (ThemeRegistry.ThemeInfo info in ThemeRegistry.AllThemes)
+		{
+			IReadOnlyDictionary<ImGuiCol, Vector4> palette = mapper.MapTheme(info.CreateInstance());
+
+			Assert.AreEqual(1f, palette[ImGuiCol.TabSelectedOverline].W, $"{info.Name}: the focused tab's overline is not opaque");
+			Assert.AreEqual(0f, palette[ImGuiCol.TabDimmedSelectedOverline].W, $"{info.Name}: an unfocused window's selected tab draws an overline");
+			AssertDistinct(palette, ImGuiCol.TabDimmedSelectedOverline, ImGuiCol.TabSelectedOverline, info.Name);
+		}
+	}
+
 	private static void AssertDistinct(IReadOnlyDictionary<ImGuiCol, Vector4> palette, ImGuiCol first, ImGuiCol second, string themeName) =>
 		Assert.IsGreaterThan(1f / 255f, Vector4.Distance(palette[first], palette[second]), $"{themeName}: {first} is drawn in the {second} color");