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

3 files changed, 24 insertions, 0 deletions

diff --git a/src/gui/kernel/qapplication.cpp b/src/gui/kernel/qapplication.cpp
index 5c333b0..3303800 100644
--- a/src/gui/kernel/qapplication.cpp
+++ b/src/gui/kernel/qapplication.cpp
@@ -2540,6 +2540,13 @@ void QApplication::setActiveWindow(QWidget* act)
         sendSpontaneousEvent(w, &activationChange);
     }
 
+#ifdef QT_MAC_USE_COCOA
+    // In case the user clicked on a child window, we need to
+    // reestablish the stacking order of the window so
+    // it pops in front of other child windows in cocoa:
+    qt_cocoaStackChildWindowOnTopOfOtherChildren(window);
+#endif
+
     for(int i = 0; i < toBeDeactivated.size(); ++i) {
         QWidget *w = toBeDeactivated.at(i);
         sendSpontaneousEvent(w, &windowDeactivate);
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
diff --git a/src/gui/kernel/qt_cocoa_helpers_mac_p.h b/src/gui/kernel/qt_cocoa_helpers_mac_p.h
index 44fb4f0..c6c2db2 100644
--- a/src/gui/kernel/qt_cocoa_helpers_mac_p.h
+++ b/src/gui/kernel/qt_cocoa_helpers_mac_p.h
@@ -148,6 +148,7 @@ void qt_cocoaChangeOverrideCursor(const QCursor &cursor);
 // These methods exists only for supporting unified mode.
 void macDrawRectOnTop(void * /*OSWindowRef */ window);
 void macSyncDrawingOnFirstInvocation(void * /*OSWindowRef */window);
+void qt_cocoaStackChildWindowOnTopOfOtherChildren(QWidget *widget);
 #endif
 void qt_mac_menu_collapseSeparators(void * /*NSMenu */ menu, bool collapse);
 bool qt_dispatchKeyEvent(void * /*NSEvent * */ keyEvent, QWidget *widgetToGetEvent);