I would greatly benefit from this as well. It would save immense time when deleting or moving numerous adjacent keyframes. I imagine it’s on the radar since rectangle select on timeline was added a while ago. It’s quite a similar concept, though I imagine the code is in a very different place and can’t super easily be adapted from one to the other.
A recent post about being able to guide motion tracking with manually place keyframes is a good example use for this. If there are “trouble areas” in the motion tracking keyframes, hundreds of them could be selected and deleted, then manual keyframes filled in.
3 methods would be cool
rectangle select
click on first one, SHIFT+click on last one to select everything in-between
CTRL+click to add any arbitrary keyframes to selection before doing stuff to them all