. simplify the interface FrameBase to make it easier to implement it for different cases (remove HDC and make parameters more explicit)
. remove functions which are only called on a Win32Frame (in which case a cast is guaranteed to succeed)
. otherwise there is the risk that every FrameBase implementation wants to add its own variants.
. FrameBase::FrameRefreshStatus() simplify implementation: pass all flags explicitly
6cffb30330