Buffer issue PropScrollbar inside AdvPanel?

I am using a TPropScrollbar inside a TAdvPanel, on entering the scrollbar it turns black and blends back to normal again. A TPropScrollbar not inside a TAdvPanel, e.g. directly on the form or inside a TPanel does not do that. When turning off the DoubleBuffered attribute of the scrollbar, the problem is gone. I clicked together a simple form like described above, should be easily reproducable. BTW: I am using the latest components.

Same thing happens e.g. on the TAdvSmoothImageListBox, however there I do not have the option to turn off double buffering of the scrollbar.

Also in some cases the scrollbar does not go black but seems to blitter the last clicked area, e.g. from a THTMLTreeView - feels like a shared buffer and looks odd.