Merge remote-tracking branch 'origin/tqtc/lts-5.15.5' into tqtc/lts-5.15-opensourcev5.15.5-lts-lgpl

Change-Id: I0cdb390124e783dc9cd832a9954baa76a0e9eb6b

1 files changed, 18 insertions, 4 deletions

diff --git a/src/widgets/widgets/qdockwidget.cpp b/src/widgets/widgets/qdockwidget.cpp
index 4663eda9eb..807d84db95 100644
--- a/src/widgets/widgets/qdockwidget.cpp
+++ b/src/widgets/widgets/qdockwidget.cpp
@@ -973,13 +973,27 @@ bool QDockWidgetPrivate::mouseMoveEvent(QMouseEvent *event)
             && mwlayout->pluggingWidget == nullptr
             && (event->pos() - state->pressPos).manhattanLength()
                 > QApplication::startDragDistance()) {
-            startDrag();
-            q->grabMouse();
-            ret = true;
+
+#ifdef Q_OS_MACOS
+            if (windowHandle()) {
+                // When using native widgets on mac, we have not yet been successful in
+                // starting a drag on an NSView that belongs to one window (QMainWindow),
+                // but continue the drag on another (QDockWidget). This is what happens if
+                // we try to make this widget floating during a drag. So as a fall back
+                // solution, we simply make this widget floating instead, when we would
+                // otherwise start a drag.
+                q->setFloating(true);
+            } else
+#endif
+            {
+                startDrag();
+                q->grabMouse();
+                ret = true;
+            }
         }
     }
 
-    if (state->dragging && !state->nca) {
+    if (state && state->dragging && !state->nca) {
         QMargins windowMargins = q->window()->windowHandle()->frameMargins();
         QPoint windowMarginOffset = QPoint(windowMargins.left(), windowMargins.top());
         QPoint pos = event->globalPos() - state->pressPos - windowMarginOffset;