1 files changed, 4 insertions, 1 deletions
diff --git a/src/plugins/platforms/cocoa/qcocoawindow.mm b/src/plugins/platforms/cocoa/qcocoawindow.mm
index 6e2d446898..69d192b4f5 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.mm
+++ b/src/plugins/platforms/cocoa/qcocoawindow.mm
@@ -567,7 +567,10 @@ void QCocoaWindow::setWindowFlags(Qt::WindowFlags flags)
     Qt::WindowType type = static_cast<Qt::WindowType>(int(flags & Qt::WindowType_Mask));
     if ((type & Qt::Popup) != Qt::Popup && (type & Qt::Dialog) != Qt::Dialog) {
         NSWindowCollectionBehavior behavior = m_view.window.collectionBehavior;
-        if ((flags & Qt::WindowFullscreenButtonHint) || m_view.window.qt_fullScreen) {
+        const bool enableFullScreen = m_view.window.qt_fullScreen
+                                    || !(flags & Qt::CustomizeWindowHint)
+                                    || (flags & Qt::WindowFullscreenButtonHint);
+        if (enableFullScreen) {
             behavior |= NSWindowCollectionBehaviorFullScreenPrimary;
             behavior &= ~NSWindowCollectionBehaviorFullScreenAuxiliary;
         } else {