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

[Xing Tu]

>It is not really that both groups were separated after the second "undo" -  what it really is, is just
>like an Oracle database "commit"...
thanks for clarifying. it makes sense

>are you referring to section 41.3 Trim Feature with Drag Handle, Button 3?
yes. the operations of mouse buttons 1,2,3 with the drag handle should
all apply to grouped clips