Cocoa: Active QDockWidget does not stay on top of inactive QDockWidget

If a window has several child windows, it was not be possible to
click on a child window to make it stack in front of the other
children. The reason is that cocoa held a fixed stacking order of
the child windows (sub-windows). This patch will release, and then
reestablish, the stacking order of the children upon acitvation.

Task-number: QTBUG-11780
Reviewed-by: prasanth
(cherry picked from commit 44e11692549f1d6a4fed01066a06085dacfaa444)

1 files changed, 16 insertions, 0 deletions

diff --git a/src/gui/kernel/qt_cocoa_helpers_mac.mm b/src/gui/kernel/qt_cocoa_helpers_mac.mm
index 3fc27f4..647cb86 100644
--- a/src/gui/kernel/qt_cocoa_helpers_mac.mm
+++ b/src/gui/kernel/qt_cocoa_helpers_mac.mm
@@ -1527,6 +1527,22 @@ void macSyncDrawingOnFirstInvocation(void * /*OSWindowRef */window)
         [theWindow display];
     }
 }
+
+void qt_cocoaStackChildWindowOnTopOfOtherChildren(QWidget *childWidget)
+{
+    if (!childWidget)
+        return;
+
+    QWidget *parent = childWidget->parentWidget();
+    if (childWidget->isWindow() && parent) {
+        if ([[qt_mac_window_for(parent) childWindows] containsObject:qt_mac_window_for(childWidget)]) {
+            QWidgetPrivate *d = qt_widget_private(childWidget);
+            d->setSubWindowStacking(false);
+            d->setSubWindowStacking(true);
+        }
+    }
+}
+
 #endif // QT_MAC_USE_COCOA
 
 QT_END_NAMESPACE