qnswindow (-backgroundColor) - return 'clear color' for Qt::Popup

That's what we initially did for borderless windows and we need it in order
to draw rounded corners for context menus.

Fixes: QTBUG-106108
Change-Id: I6e4254b714ad7a094aa295546d5ac7fba5e21b13
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit 6a839e0ae4cb1eddd290d64b152a2571f3586ed2)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/src/plugins/platforms/cocoa/qnswindow.mm b/src/plugins/platforms/cocoa/qnswindow.mm
index cce76e4b20..8d4a0617de 100644
--- a/src/plugins/platforms/cocoa/qnswindow.mm
+++ b/src/plugins/platforms/cocoa/qnswindow.mm
@@ -296,8 +296,13 @@ OSStatus CGSClearWindowTags(const CGSConnectionID, const CGSWindowID, int *, int
     // we assume that if you have translucent content, without a
     // frame then you intend to do all background drawing yourself.
     const QWindow *window = m_platformWindow ? m_platformWindow->window() : nullptr;
-    if (!self.opaque && window && window->flags().testFlag(Qt::FramelessWindowHint))
-        return [NSColor clearColor];
+    if (!self.opaque && window) {
+        // Qt::Popup also requires clearColor - in qmacstyle
+        // we fill background using a special path with rounded corners.
+        if (window->flags().testFlag(Qt::FramelessWindowHint)
+            || (window->flags() & Qt::WindowType_Mask) == Qt::Popup)
+            return [NSColor clearColor];
+    }
 
     // This still allows you to have translucent content with a frame,
     // where the system background (or color set via NSWindow) will