Comment 1 for bug 514317

actual code is:
   elif keyname == "z":
    # undo
    if event.state == gtk.gdk.CONTROL_MASK | gtk.gdk.MOD2_MASK:
     self.on_tlbUndo_clicked(widget)

that doesn't work if bloc_num on keyboard is not activated.

how about using simply

if event.state == gtk.gdk.CONTROL_MASK

this works on my system, but could this cause problems in some configuration?