This allows using the scrollbar when there are lots of usages set for
the certificate.

This makes the two static control borders between the three regions on
the general page appear to be the same height.

Tests show that in ddrawex.dll it is legal to create a surface with
both DDSCAPS_VIDEOMEMORY and DDSCAPS_SYSTEMMEMORY flag set. A surface
created that way shows different behavior in IDirectDrawSurface::GetDC.

This allows us to cleanly implement the differences between ddraw.dll and
ddrawex.dll without private functions and if checks if an object was created
by ddraw or ddrawex. A similar wrapper will be added for IDirectDrawSurface.

cryptui: Refresh store display when a tab is switched or the purpose selection is changed in the certificate manager dialog.