MainFrm: remove outdated UNREFERENCED_PARAMETER()
MainFrm: detect popup menu hiding more correctly

It generated false detection on ui preset change
MainFrm: reorder OnFilePostOpenmedia()

Fixes #3753
Resize on EC_VIDEO_SIZE_CHANGED only in MLS_LOADED

Should fix double resize when opening videos
Fix unchecked dynamic_cast warnings

CID 1130727-1130738