As it apparently does not work you will have to find a workaround.
I suggest you create a new variable
var mouse_ent_clickable = 1;
which is set to 1 if and only if the mouse position is valid (which obviously includes being outside of the dimensions of the panel in question).
EDIT: Then use that variable in entity click events.
Last edited by Superku; 03/02/15 17:01.