$PLOT->CanvasBind("<Double-Button-3>",
                   [sub {
                    print "Button 3 pressed";
                        my ($canv,$x,$y)=@_;                         
                        my ($width,$height)=($XMAX-$XMIN,$YMAX-$YMIN);
                        $x=$canv->canvasx($x);
                        $y=$canv->canvasy($y);
                        ($x,$y)=(($x-$xzero)/$xscale,-($y-$yzero)/$yscale);
                        $XMIN=$x-$width;
                        $XMAX=$x+$height;
                        $YMIN=$y-$width;
                        $YMAX=$y+$height;
                        ($XTIC,$YTIC)=($XTIC*2,$YTIC*2);
                        plot($plot_f_ref,\$canv,$data_ref);
                        }, Ev('x'), Ev('y')]);