Painting problem when QQuickWidget used

When using the new QQuickWidget component it's having some rendering problems.
Looks like update() not called or thomething like that.
Affected elements: QWindow title, QTableView header etc.
How to reproduce:
1. Qt 5.3.0
2. Open QtCreator
3. Open "Qt Quick widget example" from "Welcome/Examples" tab.
4. Compile the project in Debug mode
5.1. Press "Run" button (see result in attached run.png)
5.2. Press "Debug" button (see DIFFERENT result in attached debug.png)

Also, when I press "Debug" button I see strange message in "Application output" - QQmlInspector: No plugin available for view ' QQuickWidget '.
I still can debug the QML code and this message not appears when I press "Run" button.