Discussing thread for this issue :
http://forum.cockos.com/showthread.php?t=33413 and this thread in the General forum, where more's going on actually.
http://forum.cockos.com/showthread.php?t=43344
The primary request is this :
We request that this behaviour be implemented and be the default.
Many editors that are Reaper users and the editors many Reapers users have talked to all say the same thing. This current behaviour costs every one of us a lot of extra time in editing.
We can't be kind about this. It's one of those 'duh' things that everyone feels the designers of Reaper should have spotted in the first place, had just a little more research been done. Of course we're sitting on a high horse looking back with plenty of knowledge and experience of what this current behaviour incurred. But that doesn't make it any better either :) .
The requested behaviour should apply to both sides of the item.
It would be best if Reaper used the last state of an item as a basis for re-revealing its contents when an item that was placed on it partially was moved away. Whatever the green item was like before the red one covered it partially, that would re-revealable.
What then ?
Fade and Trim handles (!very important! there should be no hidden handles!!)

Visible => normal item behaviour. The hidden stuff has to be re-revealed!
Moving the Green item left
Moving the Green item right
Moving the Red item left
