Using A # In A Dummy Onclick Plus Page Reload, Part 2

I asked about this a while ago, and got a great answer and a reference
to http://www.javascripttoolbox.com/bestpractices/new.php. I just need
to override onclick and return false. No biggie!

However, I discovered that my code worked fine in IE (no # in URL after
click), but not in FF (# appears in URL after click). Can anyone tell
me why?

if(link.attachEvent) { eval("link.attachEvent('onclick',function() {
GB_show('" +part.strDesc +"', '" +INFO_URL_BASE+part.infoUrl +"', 470,
600); return false; },false)"); }

else { eval("link.addEventListener('click',function() { GB_show('"
+part.strDesc +"', '" +INFO_URL_BASE+part.infoUrl +"', 470, 600);
return false; },false)"); }