$mw->Button(
    -text    => "Save PS",
    -command => [sub {
         $canv->update;
         my @capture=();
         my ($x0,$y0,$x1,$y1)=$canv->bbox('all');
         print "$x0,$y0,$x1,$y1\n";

         @capture=('-x'=>$x0,'-y'=>$y0,-height=>$y1-$y0,-width=>$x1-$x0);
    	 $canv->postscript(-colormode=>'color',
                              -file=> "$0.ps",
			       -rotate=>0,
			       -width=>2400,
			       -height=>3400,    
			       @capture);
                               
	system("convert $0.ps $0.png");	      
      } 
  ]  )->pack;