WidgetResizeHandler: Fix case if parent's target wasn't top-level

By luck parentGeometry was in global space. Force it to be in global
space, as the target might be more nested.

Will be used by MDI, where Frame's parent is the MDI layout

src/private/WidgetResizeHandler.cpp

@@ -139,9 +139,10 @@ bool WidgetResizeHandler::mouseMoveEvent(QMouseEvent *e)
     QRect newGeometry = oldGeometry;
 
     QRect parentGeometry;
-    if (!mTarget->isTopLevel())
-        parentGeometry = KDDockWidgets::Private::parentGeometry(mTarget);
-
+    if (!mTarget->isTopLevel()) {
+        auto parent = KDDockWidgets::Private::parentWidget(mTarget);
+        parentGeometry = KDDockWidgets::globalGeometry(parent);
+    }
 
     {
         int deltaWidth = 0;