jgpaiva, I have my mouse set up similar to yours, but instead of multimedia I have it setup for firefox. The scroll down button closes tabs, scroll up button minimizes the window, scroll left and right switch tabs left and right, back and forward do their default commands, and the switch app button closes windows. It's an increadible time saver!
I think that post didn't get much attention because i simply can't communicate as well as i'd like to.
Actually, i don't have my mouse set up like that. That's a thing I invented, mouse can act just normal, it only has that layout when you press one combination, that activates "multimedia mouse", which means, that you can use your mouse as normal, and then, when you press the combination that activates that mode, the mouse buttons are bound to those functions. You press the combination again, and the mouse buttons act like they act usually.
I also have many mouse gestures in opera, for opening tabs, closing tabs, cycling tabs, opening in new pages, go page back, go page forward, etc,etc,etc, but this doesn't interfeer with it, only when i activate the mode, to pause the music, or something. Usually, i only activate it to use one function, and then, do the combination again to use my mouse as i do always
ps: sorry to be nagging you, but the first time you read my post, did you understand that it worked like i explained here?