QmlDesigner.dragTool: improve usablity of drag and drop

If the parent is not set yet we do not need to reparent, yet.

Change-Id: I2ad743e775ebac57dde1b3600ff6af6378fc9da2
Reviewed-on: http://codereview.qt.nokia.com/1408Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Marco Bubke <marco.bubke@nokia.com>

src/plugins/qmldesigner/components/formeditor/dragtool.cpp

@@ -404,7 +404,7 @@ void  DragTool::move(QPointF scenePos)
         return;
 
     FormEditorItem *containerItem = calculateContainer(scenePos - QPoint(2, 2), m_movingItem.data());
-    if (containerItem &&
+    if (containerItem && m_movingItem->parentItem() &&
        containerItem != m_movingItem->parentItem()) {
 
         m_moveManipulator.reparentTo(containerItem);