Shift on a selected layer took it out of the selection on press, so the
drag that followed had nothing to move, and with several layers selected
the grabbed one stayed behind. It now leaves the selection on release,
and only when the press didn't become a drag. Where no move can start
(a version being viewed), it still leaves on press.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
A selection and transform behaviour suite derived from public documentation, with fixes: Alt-resizing shrinks as well as grows; groups, Scale-constrained frames and multiple selections resize each layer along its own axes keeping rotation and flip; several layers flip together past an edge; a flipped layer reads back the typed rotation; resizes land on whole pixels with the pixel grid; presses inside tiny layers move them; locked layers get no handles; a marquee can start on a top-level frame's background; select inverse skips hidden layers. Adds equal-spacing snapping with labelled gaps and Cmd/Ctrl to ignore constraints while resizing a frame.
