Fix that feedback pane is shown on drag and drop from the item libarary

Reviewed-by: Thomas Hartmann
Task-Number: BAUHAUS-536

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

@@ -213,6 +213,7 @@ void DragTool::dragEnterEvent(QGraphicsSceneDragDropEvent * event)
     if (event->mimeData()->hasFormat("application/vnd.bauhaus.itemlibraryinfo") ||
         event->mimeData()->hasFormat("application/vnd.bauhaus.libraryresource")) {
         if (!m_rewriterTransaction.isValid()) {
+            view()->clearSelectedModelNodes();
             m_rewriterTransaction = view()->beginRewriterTransaction();
         }
     }