This is really weird. When I log in using google's chrome browser, on the Files tab I don't get a box next to the "choose file" button. All I get is text saying 'no file chosen'. If I happen to decide to click the text it acts like I clicked inside a browse box.
Dunno if it's a chrome thing or something b2evo can do something about, but I figure both chrome users would like to have a browse box one day ;)