Cross-browser printing iframe content

I found problem with printing iframe content in Opera. So here is my simple solution:

function print_iframe(s) {
 var iframe = window.frames[s];

 if(navigator.userAgent.indexOf("Opera") == -1) {
   iframe.focus();
   iframe.print();
 } else {
   var opera = window.open(iframe.location);
   opera.opener.focus();
   opera.print();
   opera.close();
   opera = null;
 }
}