I can't remember when that disappeared - years ago.
i think it was lost during the gui-rewrite. (the argument being, that this feature was mainly useful for Copy-Paste which - snce the rewrite - works within msg-boxes)
not really… you could open edit and close and you could do arrows up and down which you cannot do in message boxes. no need to copy in and out of pd which is more convenient.
miller's suggestion of up&down keys working in msg boxes would solve it.
best,
J