Can we find a better name? I have considered the followings.
* 'point', because "the pointer" points to the current item.
* 'shift', 'switch', 'move', etc. These are not technically correct
because the current item can change without cursor movement (--tac,
reload, search update)
* 'change' is already taken. 'change-current' feels a bit wordy and
sounds wrong, 'current-changed' is wordy and doesn't go well with the
other event names
* 'target', not straightforward
Close#3053