my ($xlock,$ylock);      # These keep track of the first coordinate clicked on
  $PLOT->CanvasBind("<ButtonPress-1>", 
                   [sub {
                        $DRAWING_IN_PROGRESS=1;
                        my ($canv,$x,$y)=@_;  
                        ($xlock,$ylock)=($canv->canvasx($x),$canv->canvasy($y));
                        $canv->delete("zoombox");
                        $canv->createRectangle($xlock,$ylock,$xlock,$ylock,-tag=>"zoombox",-outline=>'lightgray');
                   }, Ev('x'), Ev('y')]);   

  $PLOT->CanvasBind("<ButtonRelease-1>", 
                   [sub {
                        my ($canv,$x,$y)=@_;  
                        if ($DRAWING_IN_PROGRESS==1) {
                          $DRAWING_IN_PROGRESS=0;
                          $canv->delete("zoombox");

                          $xend=$canv->canvasx($x);
                          $yend=$canv->canvasy($y);
  
                          if ($xlock==$xend || $ylock==$yend){
                            $canv->delete("zoombox");
                            return 0;
                          }
                      # Convert back to real coordinates
                        
                          ($X1,$Y1)=(($xend-$xzero)/$xscale,-($yend-$yzero)/$yscale);
                          ($X2,$Y2)=(($xlock-$xzero)/$xscale,-($ylock-$yzero)/$yscale);
                          if ($X1==$X2 || $Y1==$Y2) {
                             return 0;
                          }
                          if ($X1<$X2) {
                            $XMAX=$X2;
                            $XMIN=$X1;
                          } else {
                            $XMAX=$X1;
                            $XMIN=$X2;                          
                          }
                          if ($Y1<$Y2) {
                            $YMAX=$Y2;
                            $YMIN=$Y1;
                          } else {
                            $YMAX=$Y1;
                            $YMIN=$Y2;                          
                          }  
                          plot($plot_f_ref,\$canv,$data_ref);
                          }
                        }, Ev('x'), Ev('y')]);           
  $PLOT->CanvasBind("<Double-Button-1>",
                   [sub {
                        my ($canv,$x,$y)=@_;                         
                        my ($xm,$ym,$xx,$yx)=($XMIN,$YMIN,$XMAX,$YMAX);
                        $x=$canv->canvasx($x);
                        $y=$canv->canvasy($y);
                        ($x,$y)=(($x-$xzero)/$xscale,-($y-$yzero)/$yscale);
                        $XMIN=$x-($xx-$xm)/4;
                        $XMAX=$x+($xx-$xm)/4;
                        $YMIN=$y-($yx-$ym)/4;
                        $YMAX=$y+($yx-$ym)/4;
                        ($XTIC,$YTIC)=($XTIC/2,$YTIC/2);
                        plot($plot_f_ref,\$canv,$data_ref);
                        }, Ev('x'), Ev('y')]);                          


##</code><code>##

  $PLOT->CanvasBind("<ButtonPress-3>", 
                   [sub {
                        my ($canv,$x,$y)=@_;  
                        $x=$canv->canvasx($x);
                        $y=$canv->canvasy($y);                         
                        $MOVING_IN_PROGRESS=1;
                        $canv->createLine($x,$y,$x,$y,-tag=>'zoombox');
                        ($xlock2,$ylock2)=($x,$y)
                   }, Ev('x'), Ev('y')]);  

  $PLOT->CanvasBind("<ButtonRelease-3>", 
                   [sub {
                        my ($canv,$x,$y)=@_;                         
                        if ($MOVING_IN_PROGRESS==1) {
                          $x=$canv->canvasx($x);
                          $y=$canv->canvasy($y);
                          ($x,$y)=(($x-$xzero)/$xscale,-($y-$yzero)/$yscale);
                          ($xlock2,$ylock2)=(($xlock2-$xzero)/$xscale,-($ylock2-$yzero)/$yscale);
                          $XMIN=$XMIN+($x-$xlock2);
                          $XMAX=$XMAX+($x-$xlock2);
                          $YMIN=$YMIN+($y-$ylock2);
                          $YMAX=$YMAX+($y-$ylock2);
                          plot($plot_f_ref,$plot_ref,$data_ref);                       
                          $MOVING_IN_PROGRESS=0;
                        }                                             
                   }, Ev('x'), Ev('y')]);  

##</code><code>##

  $PLOT->CanvasBind("<Double-Button-3>",
                   [sub {
                    print "Button 3 pressed";
                        my ($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')]);