A clip drag moved only the clip under the cursor (plus its graph-linked
A/V partner); the rest of the selection stayed behind. The engine now
keeps the full timeline selection (it used to collapse it to the
effect-stack's single target) and expands ClipMoveRequested to the
grabbed clip's transitive link group UNION, when the grabbed clip is
part of the multi-selection, every other selected clip and their link
groups. Each follower stays on its own track and shifts by the same
frame delta (relative positions preserved), the group-wide clamp keeps
every clip at or after frame 0, and the whole move is one undoable
entry. Followers on locked tracks are left in place.
moving_a_multi_selection_drags_the_whole_group covers two A/V pairs:
selecting both video clips and dragging one moves all four clips by
the same delta, and one undo restores them.
Mike-Solar
20535546d6