It would be great if you could trim clips without their transitions being destroyed.
I'm sure most users find it natural to start at the beginning of their clips and then work to the end, but with AVS Video Editor you need to start at the end of the clip and then work backwards to the beginning of the clip if you don't want to lose all the time that you spent perfecting the transition for the beginning of the clip.
Example:
You have 3 clips on a time line: Clip A, Clip B and Clip C.
Clip A is the first clip and it is placed at the very beginning of the time line. You then want to blend from Clip A into Clip B and do the same again for Clip B to Clip C (so there are 2 dissolves instead of using quick jump cuts).
You position Clip A on the time line and then trim it.
You then position Clip B after Clip A and spend time deciding how much they should overlap to get the transition that you want.
Once you are happy with the transition, you move forward to the end of Clip B and decide how you want to deal with that.
You see that Clip B is too long, so you trim Clip B in preparation for adding the final clip (Clip C).
However, when you trim the end of Clip B, you lose the overlap at the beginning of Clip B (between Clip A and Clip B) and there is no way to get it back other than to use 'undo' (which means that Clip B becomes un-trimmed again).
It would be much better if trimming (either at the beginning or end) of any clip did not affect the transitions.
Where the beginning of a clip has been trimmed after it has been overlapped, the same duration of overlap should be maintained, but using the new trimmed point as the start point instead (in other words the clip is shifted forward by the amount that it has been trimmed, but the exact duration of the transition is maintanted even after trimming).
It's really frustrating to have to keep going back to re-create transitions whenever you just want to remove or add a few frames to a clip. This is especially so when the clip that needs trimming is right in the middle of a long sequence of clips, because it can end up having a nock on effect right the way down the time line.