Until now, the implementation of the overrides in `SelectionBlueprint`
have been confusing to the point where I would just implement by
trial-and-error (or copying from an existing implementation). This was
due to a combination of using "object" space coordinates
(ie. the thing the `Blueprint` is operating on) and screen-space coordinates.
This change switches all event related coordinates to screen-space,
which is how we already handle rotation/scale operations. With the
introduction of other editor types where the related objects are
drawables, this also makes a lot more sense.
By moving this to a central location, we can avoid invoking the
EditorChangeHandler when there is no selection made. This helps
alleviate the issue pointed out in
https://github.com/ppy/osu/issues/11901, but not fix it completely.
This was firing regardless of whether the start time was changed, such
as where beat snap provided the same time the object already has.
The case where a change actually occurs is already handled by
EditorBeatmap (see `startTimeBindables`), so it turns out this local
handling is not required at all.
Closes https://github.com/ppy/osu/issues/10672.
In two minds about how this should be implemented but went in this
direction initially. The other way would be to add local handling of
Shift-Right Click inside PathControlPointPiece (which is already doing
mouse handling itself).