Making Opera your default browser

I've installed Opera 10.63. It's cool :D And I decided to use it as default browser on my system (Ubuntu).

But not like the Opera version for Windows platform. I can't find the option to set Opera as default browser :| After "research", I found: there is no options to set in Opera browser, you only can set by go to System > Preferences > Preferred Applications (assume you using Gnome). In the Internet tab, under Web browser label, choose Opera on dropdown box :)