!!! You should manually to set an option opera:config#PersistentStorage|UserJSStorageQuota" >= 500 Kb
Some Opera bugs:
After installation of the extension, all pages should be reloaded (via restart the browser).
DSK-316102 (User JS not loaded when page loads too fast)
CORE-33382 (User JS code not run in extensions if page does not include a script tag)
CORE-33775 (User JS extensions don't run on HTTPS sites)
DSK-318727 (Extension blocks execution of userjs)
DSK-317999 (Extension + UserJS blocks page loading)
Blocking scripts from other domains that are 99% of cases are advertising.
Blocking of page elements, including text ads.
Import subscriptions AdBlock Plus EHH.
Helper mode for Opera's "Content blocker". Easy blocking iframes and scripts.
Enable/disable blocking with the "quick button" in the right bottom corner of a page.
Preferences - Alt+Shift+P
Block ads - Alt+Shift+A
Block element - Alt+Shift+B
Unblock - Alt+Shift+U
Unblock latest element - Alt+Shift+L
Q: It doesn't work for me.
A: 1) Please, read the list of known bugs. Look on the current page url. Yes, this is a https page.
2) Set UserJSStorageQuota. It's really needed!
3) If it doesn't help, post the log from Error Console to the support page.
Q: Is this a replacement for the content blocker/urlfilter.ini?
A: Nope. This is an _addition_ to Opera's content blocker.
Q: How to update urlfilter.ini?
A: This is impossible with the current extension api. However, there is a good java application: http://my.opera.com/urlfilterdownloader/blog/
Q: Is it actually block ads or just hide it?
A: Opera doesn't load the hidden content (exclude iframes).
Q: There are many bugs in Opera 11 Alpha...
A: You can use userjs-version noads.js with the stable Opera 10.63.