Add Shift+[ / +] as native shortcuts to move selected layers to playhead, keeping relative offsets

I currently use pt_shiftlayers a LOT to move 'blocks' of layers (the 'Shift selected layers' option), so the first or last in-point moves to the playhead and the other selected layers move with it, but keep their relative offsets in time.

I'd like to suggest that Shift+[ and Shift+] would perform this task natively. It would keep the moving layers to playhead behaviour on the same keys ( [ and ] ), but add an extra level of functionality. Much the same way as we can now use Shift+j and Shift+K to move through keys for the selected properties only.

Cheers!