This is a known bug in Opera. In addition to the above ideas for workarounds, you may want to play with something like this:
var clone=document.documentElement.cloneNode(true)
var win=window.open('about:blank');
win.document.replaceChild(clone, win.document.documentElement);
win.print();
I have not tested this but it should create a copy of the page in a popup window and print it, without having to load the content a second time from the server or loosing any DOM modifications you may want printed.