[Cin] Ungrouping of video and audio clips after some edits

[Xing Tu]

Yes, exactly. It was the only problem I stumbled upon when trying to
do a basic project. If that gets implemented, then as far as basic
editing goes, cin would be perfect. Actually, one more thing would be
if "drag source only" would also apply to groups. In my opinion these
features should be prioritized since cin is after all an NLE and these
are key components in such a system.