Ignore modkey+click on unmapped windows to avoid rare crash, e.g. with LibreOffice slide show (#117)

Author: Seeker04

src/plwm.pl

@@ -1422,8 +1422,7 @@
 
 	% left or right mouse clicked
 	;(Button = Button1 ; Button = Button3) ->
-		nb_getval(bars, Bars),
-		(Subwin =\= 0, \+ member(Subwin, Bars) ->
+		(Subwin =\= 0, win_mon_ws(Subwin, _, _) ->
 			focus(Subwin),
 			raise(Subwin),
 			(plx:x_get_window_attributes(Dp, Subwin, [X, Y, W, H], Status), Status =\= 0,