I've found that it's a bit annoying to see a simple "about:blank" in the address bar when the main document has been blocked (my custom builds, unlike ABP, allow filters with no type specifiers to block the main document), so I've reverted that behavior to the ABP standard by sending "cancel:true"; this means that you should still see the blocked URL in your address bar and you'll see the standard "blocked by an extension" message.
It seemed preferable to rolling my own, returning something like
Code: Select all
{redirectUrl:"data:text/html,<!doctype html><head><title>Blocked by Adblock Plus</title></head><body><p>Navigation to the URL "+details.url+" has been blocked by Adblock Plus because it matched one of your filter subscriptions or custom filters; if you believe this was in error, please check your custom filters and contact the subscription authors.</p></body></html>"}
which would still have the problem (which redirecting to about:blank has) of conflicting with ScriptSafe (which occasionally blocks the main document when it is not trusted, although usually it just keeps scripts, including inline scripts, from being run, while letting the rest of the document load).
There's a buzzin' in my brain I really can't explain; I think about it before they make me go to bed.