MiniView window was designed around the times of Windows 98/2000.
Also, there was unfortunate design decision made to use buttons integrated with title bar.
Those two facts causes problems with newer Windowses where theming was implemented. While all the dialog boxes in CH uses those theming extensions, the miniview dialog cannot because of the custom drawing.
We need to redesign this window to use the system theme and to avoid similar problems in the future.
Most probably the buttons will need to be removed from title bar and placed somewhere else.