The strip handed the drag to the dock area via cx.emit, which is
deferred — the dock's drag state was created a dispatch too late, so
the hovered target was never recorded and drops were no-ops. The dock
area now lazily begins the drag in its own capture-phase handler;
drops onto the root edge from the panel's own group split the tree
instead of being swallowed as self-drops.
Mike-Solar
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