Uh, I hope they will find a way to replace it with more specific handlers, so it will be less resource hungry to detect UI changes. Somewhere I read that one of the major problems with having the modal detection running was that it made Blender unable to do temp backups. Maybe that could be solved another way than completely removing it? But that said, I feel your pain. I see your remark about the issue(and other peoples), and no reply…
Anyway, the biggest problem with previewing trimming is properly the slow preview update speed.
Maybe it could be set-up as a trimming mode, activated by hitting a key or button.
Which will make the playhead jump to the nearest cut. If it is the beginning of a cut, then check if there are any non-audio strips on the previous frame, and if it is the last frame of a strip, then do the opposite. If there are any visual-strip on the offset-frame then split the preview area(just need one) in two vertically(
area_split ( direction=‘VERTICAL’ , factor=0.5 , mouse_x=-100 , mouse_y=-100 )) and set-up the overlay frame mode(one player: reference and the other: current and -1 frame offset) in the preview areas.
Then using the mouse or your new excellent nudging/playback controls the user will find the precise frame to trim i/o. Then like “grab” - left mouse/Esc: cancel - right mouse/Enter: accept changes - the trim mode will be closed and the preview area will merge back into one in its original size.
On the centering, I don’t know if this script might have some useful elements, it is for converting the 3d view into a camera, which is centered and scaled - like new video preview if that was what you meant? https://gist.github.com/tin2tin/b95fa8686db3a03565f9064b692c71d5
But as I wrote, in the beginning, the Blender video previewing code may not be fast enough for this operation anyway, so most of all I’m just curious about how it would work, though I’m a bit skeptic, about it actually would be useable(fast enough).