To expand on Wims' example:

Code:
dialog t_mirc {
  title "Ga"
  size -1 -1 200 200
  icon 1, 50 50 50 50, $mircexe , 2
}
on *:dialog:t_mirc:sclick:1: did -g $dname 1 1 $qt($mircexe)
on *:dialog:t_mirc:uclick:1: did -g $dname 1 2 $qt($mircexe)