Cocoa: Properly remove content view from its superview in setNSWindow()

-[NSWindow setContentView:] doesn't make assupmtions about where that
view comes from, and just attaches it to the window. We need to make
sure we detach it from its previous window by calling -[NSView
removeFromSuperview], or the previous NSWindow may keep references to
the view. This can be an  issue if the view is deleted right after.

Task-number: QTBUG-39628
Change-Id: I152dedcb64ac044d8ca290c9996b388809e2477b
Reviewed-by: Timur Pocheptsov <Timur.Pocheptsov@digia.com>
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoawindow.mm b/src/plugins/platforms/cocoa/qcocoawindow.mm
index 19d0f7a987..96c882887e 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.mm
+++ b/src/plugins/platforms/cocoa/qcocoawindow.mm
@@ -1477,7 +1477,11 @@ void QCocoaWindow::setNSWindow(QCocoaNSWindow *window)
 {
     if (window.contentView != m_contentView) {
         [m_contentView setPostsFrameChangedNotifications: NO];
+        [m_contentView retain];
+        if (m_contentView.superview) // m_contentView comes from another NSWindow
+            [m_contentView removeFromSuperview];
         [window setContentView:m_contentView];
+        [m_contentView release];
         [m_contentView setPostsFrameChangedNotifications: YES];
     }
 }