js break point never hit , can not switch to other modes when c++ / js debugging

1. Create a hybrid QML/C++ project (Qt Quick Application). Leave shadow build on.
2. Select a Qt Version >= 4.8.0.
3 .Check that 'Enable QML debugging' is checked in qmake step on the Build configuration page.
4. Rebuild.
5. Make sure "C++" and "QML" Debugging under "Debugger Settings" are enabled in Run Settings.
6. Place a breakpoint in main.cpp, before QGuiApplication object is constructed.
7. Place a breakpoint in the mouseArea.onClicked handler in main.qml.
8. Start debugging the project.
9. Run again after hitting main.cpp break point
10. main.qml view opens , can not switch to any mode , some title of views are constantly tearing .

Js breakpoint not hit.