QWindowsTheme: only set inactive accent color to Window if not set

Otherwise it incorrectly changes to a white-ish color when the window
becomes inactive, when native apps keep the accent color.

Fixes: QTBUG-116826
Change-Id: I3837e7ca93a494e60dbe5f1b7f8607b3dd16d29e
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

1 files changed, 6 insertions, 2 deletions

diff --git a/src/plugins/platforms/windows/qwindowstheme.cpp b/src/plugins/platforms/windows/qwindowstheme.cpp
index 4fccec98fb..636479b1e3 100644
--- a/src/plugins/platforms/windows/qwindowstheme.cpp
+++ b/src/plugins/platforms/windows/qwindowstheme.cpp
@@ -591,8 +591,12 @@ QPalette QWindowsTheme::systemPalette(Qt::ColorScheme colorScheme)
                         result.color(QPalette::Inactive, QPalette::Window));
         result.setColor(QPalette::Inactive, QPalette::HighlightedText,
                         result.color(QPalette::Inactive, QPalette::Text));
-        result.setColor(QPalette::Inactive, QPalette::Accent,
-                        result.color(QPalette::Inactive, QPalette::Window));
+        // Only set this if it hasn't been set.
+        if (!result.isBrushSet(QPalette::Inactive, QPalette::Accent)) {
+            // We set Accent to Window to match the behavior of Windows 11.
+            result.setColor(QPalette::Inactive, QPalette::Accent,
+                            result.color(QPalette::Inactive, QPalette::Window));
+        }
     }
 
     const QColor disabled = mixColors(result.windowText().color(), result.button().color());