MainFrame: fix aero-snap misdetection

Refs #4284
MainFrame: don't reset position when aero-snapped
MainFrame: don't access class as memory chunk
MainFrame: adjust auto-zoom logic yet more

We auto-zoom when we loose the video during playback.
So it makes sense to auto-zoom when we regain it too.
StatusBar: flickerless paint
InfoBar: fix aggressive relayout

Better performance. Fixes some visual glitches.
MainFrame: don't exit d3dfs in OnFilePostOpenmedia