http://bugs.winehq.org/show_bug.cgi?id=13891
--- Comment #34 from Vitaliy Margolen vitaliy@kievinfo.com 2009-11-06 00:25:21 --- (In reply to comment #33) No, your solution will break some brilliant works of unnamed programmers who think the only browser in existence was, is and will always be IE6. That registry is set in stone and can not be altered in any way shape and form even by Microsoft themselves. That there is no such thing as API and everything have to be done by hand...
In short - some dumb programs take that registry entry, append URL to it and execute it. Obviously they don't know how to parse "%1" and this will result in invalid command line.