Strange activities of debugger when debugging Qt Quick application

There are three strange activities below.

Reproduction steps:

1. Create a Qt Quick application. Both "Built-in elements only(for all
platformss)" and "Qt Quick Components for Meego/Harmattan" is ok.
2. Set Debug mode. Set a breakpoint in main.cpp
3. Start debugging. The debugger stop at the first line of main.cpp not
the breakpoint. It is also a bug and has been reported before.
4. Press F10 to step over, it does not work. All the debug button are
disabled see debug.png.

note: If right click the project name on the project tree and select
"Set as Active Project" the debug button can be enable.

5. If I continue debugging, when the qml window show and click it.
The window disappear which is normal but the debugger automatically
start again and stop at the first line of main.cpp.

debug log is in debuglog.txt.