+ <signal name="key_press_event" handler="on_puzzlegrid_key_press_event"/>
+ <signal name="focus_in_event" handler="on_puzzlegrid_focus_in_event"/>
+ <signal name="button_release_event" handler="on_puzzlegrid_button_release_event"/>
+ <signal name="focus_out_event" handler="on_puzzlegrid_focus_out_event"/>