Implement dragging animation Audio Playback keyframes across tracks

[CookieBadger]

Describe the project you are working on

A 2D rythm-platformer (it's complicated)

Describe the problem or limitation you are having in your project

When I have an AnimationPlayer with several tracks of the same type, I sometimes would like to move a keyframe from one track to another one. The main use case for this is audio tracks. It might happen on other tracks as well, though.

Describe the feature / enhancement and how it helps to overcome the problem or limitation

When clicking and dragging a keyframe and hovering over another track, it should get removed from the first track and added to the second track on the position of the cursor. For audio tracks, I find this very intuitive, but for other track types, it could have the side-effect of accidentally moving keyframes, I'm not sure about it. But since for audio you also drag files onto the track (maybe onto the wrong one, by accident), it makes sense to have such a feature there.

Describe how your proposal will work, with code, pseudo-code, mock-ups, and/or diagrams

Explained in the previous section.

If this enhancement will not be used often, can it be worked around with a few lines of script?

I don't think an Editor plugin can do that.

Is there a reason why this should be core and not an add-on in the asset library?

AnimationPlayer is core and needs more usability :)