Some buttons aren't completely clickable

Steps to reproduce:

• have a Qt Quick Application at hand
• switch to QmlProfiler
• profile the app to gather some data
• check the buttons at the top of the Timeline (not the buttons integrated into the debugger toolbar)
• some rows of pixels (somewhat below the middle of the button?) aren't clickable (you can see this also while hovering across the buttons that at these rows the button(s) lose their hover highlight)

Note: this problem seems to vanish if you undock the respective view. So, this might be somehow related.