$canvas->Tk::bind("<Control-Motion>", [ \&set_coord, Ev('x'), Ev('y') ]);
	
    #no just the first:
    #$canvas->Tk::bind('<Button1-Motion>', [ \&set_coord, Ev('x'), Ev('y') ]);

    # no just the first
    #$canvas->Tk::bind('<B1-Motion>', [ \&set_coord, Ev('x'), Ev('y') ]);

    # wrong: extra characters after detail in binding at
    #$canvas->Tk::bind('<Button-1-Motion>', [ \&set_coord, Ev('x'), Ev('y') ]);

    # wrong: bad event type or keysym "Button1"
    #$canvas->Tk::bind('<Button1><Motion>', [ \&set_coord, Ev('x'), Ev('y') ]);

    # ok after Button-1 (not holding it) until for example Button-3
    #$canvas->Tk::bind('<Button-1><Motion>', [ \&set_coord, Ev('x'), Ev('y') ]);