For example, let's say I have this clip which is technically 4 bars long but doesn't quite fill out the entire 4 bar block. Now I have to slip edit both the start and end to make it into a proper 4 bar loop that I can then copy without having to switch to snap by. Well what if there were some keyboard shortcut to automatically make a clip fill out its 4, 8 or 16, whichever, segment? That would be swell now, would it.

I guess it would be a sort of Quantize function for clip boundaries. I would use it. I often record an 8 bar section of guitar with a bit of 'spill' at the end, and when arranging the track it's useful to be able to quickly set the clips to exactly 8 bars in length,

Clip Quantize, that's exactly what it should be called, yes.

Voted. Very good idea.