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

[Xing Tu]

> I think that you are omitting the fact that all track streams must be independent.  If they are always bound in the way you seem to describe, it would not be possible to create arbitrary alignments.  This is essential, since the result must support all possible media placements.

I think Good Guy made that clear in a previous message and it makes
sense. However, when the video "stream" is *grouped* with the audio
"stream", the only thing that's possible is moving them around (or
performing the operations available in the middle click menu). It's
counter-intuitve that when trying to extend or shorten the length of
the video stream, the corresponding audio stream remains unaffected
(and vice-versa) despite being grouped.

> You can still get what you want by switching from Arrow mode (Drag and Drop) to Ibeam mode (Cut and Paste)...

I can see how this would work, but it comes back to the original
problem of having to perform multiple actions. In addition to what you
said about having to keep in mind which tracks are (dis)armed, the
user would also be required to count the number of frames they removed
(or added when using the "drag all following edits" action) from the
video stream and do the same for the audio stream. It's clear that
this is inefficient.

> The undo is specifically for "edit" operations and grouping is not considered an edit but the state at the time of the undo edit is reverted to the last commit for an editing operation - this is what you show in your video.

That's what I thought after thinking for a bit... but can you explain
why both groups were separated after the second "undo"?

> There is no obvious way, but you can do a Ctrl-C from the terminal window where you started running cin and it will create a /tmp/cin...dmp file that contains the last 32 UNDO entries

Okay, so that's why ctrl-c has to be done twice to exit. It'd
certainly be useful if you guys can figure this one out.

Thank you guys again, though. It's really appreciate from some dumb
user that you guys are even working on this project and have made all
the improvements so far.