MenuBar in DockWidget changes size

[wamo]

I have a problem with a MenuBar of a DockWidget

It does not show the correct margin (left):
!http://img98.imageshack.us/img98/7328/qmenubarbug.png(QmenuBar)!

Now if i set the CSS Style:
@QMenuBar
{
margin-left: 5px;
}@

It shows the correct margin (right part of the image) but the MenuBar suddenly gets much bigger. If i resize it manually with "height" property then the menus get lost like there is no space.

Any idea how to fix it or track the root?