Code:
function show_target()
{
my.passable = on;
my.invisible = on;
while (mouse_left == 1) {wait (1);}
while (mouse_left == 0) {wait (1);}
ent_remove (me);
}


Lite-C Tut. 1 Lite-C Tut. 2 Lite-C Tut. 3 (en)
Shader Tutorial (ger)

http://www.slindev.com