Frequently Asked Questions - Advanced functionality
What can I do with filter subscriptions?
Filter subscriptions let you download filters from some location on the web or on your disk automatically every day. These filters are stored in a separate group and don’t interfere with the filters you define yourself. This way you can use filter lists other people create and maintain while still having your own additions to those. You can also disable all filters from the subscription without removing it if you have the suspicion that the filters are causing problems.
What does “Collapse blocked elements” do?
Usually when an advertisement is blocked it still shows up as empty space on the page. With this option enabled Adblock Plus will try to remove this empty space after blocking something.
What does “Show tabs on Flash and Java” do?
Web pages can contain objects that are displayed by external plugins like Flash or Java. These objects have a context menu of their own, that’s why blocking them via context menu isn’t possible. When this option is enabled Adblock Plus will show a button saying “Block” at the upper right (lower right if there isn’t enough space) corner of such an object. You can click this button to block the object.
Why was “DIV blocking” removed?
It wasn’t really removed, but rather replaced by a more powerful and more efficient feature: element hiding. Unfortunately you can’t keep the old DIV blocking rules, they need to be translated into element hiding rules — which are similar but not quite the same. So why couldn’t we simply keep DIV blocking? There is a number of important reasons:
- DIV blocking doesn’t hide whatever it is “blocking” immediately but only after the page finished loading. This can take a while, especially for pages that load counters from external sites, and banners that disappear after something like a minute are simply not acceptable. With element hiding the elements are hidden immediately, actually they are not shown at all.
- DIV blocking needs to search the whole page for matching elements after the page loads. This takes a while of course, with the result being that whenever people complained about Adblock Plus 0.5 being slow they usually meant DIV blocking. Element hiding uses browser’s built-in mechanisms that are very efficient.
- There are no special “DIV blocking rules”, DIV blocking applies all rules to all page elements in question, without exceptions. Rules like
*/ad/*that were never meant for DIV blocking are applied as well. The result in this special case is that a page that has the string “/ad/” in its address becomes unusable — DIV blocking hides everything on this page. It seems that home banking applications were a common victim of this “feature”. Element hiding on the other hand introduces a clear separation between “normal” filters and element hiding rules, so that this kind of problem should never happen. - It has to be said that there is nothing special about the DIV tag in HTML. It is often used for so called “layer ads” but other HTML elements can be (and are) used as well. Element hiding doesn’t distinguish between HTML tags and can hide any of them.
There is one more advantage of element hiding: you can use the full power of CSS. Using raw CSS you can hide elements not only based on their own properties but also based on properties of neighboring elements and the element’s relation to them. There are disadvantages as well of course: element hiding uses a whole new syntax for its filters whereas DIV blocking filters were built in exactly the same way as “normal” filters — with wildcards and regular expressions. Also, suggestions for DIV blocking were shown in the list of blockable elements, you didn’t have to use external solutions like DOM Inspector. These could be quite a few suggestions however, making the list very difficult to scan through.
Why was “Site blocking” removed?
“Site blocking” was a feature in Adblock 0.5 that allowed filters to be applied to web pages as a whole and prevent you from navigating to a page that matched some filter on your list. The main reason why this function wasn’t kept in Adblock Plus 0.6 is: preventing you from seeing a page you explicitly requested doesn’t have much to do with ad blocking. Also, the way it was implemented in Adblock was flawed in a number of ways:
- Instead of leaving you on the page where you were before, Adblock would show you an ugly error page.
- The way this error page was displayed often caused browser issues like dysfunctional tabs.
- Any filter on your list was used for site blocking even though only a few were intended to be.
Yet there are still people who need this functionality. And therefore I am happy that there is an extension now that can prevent the browser from navigating to certain web pages better than Adblock ever did: BlockSite. This extension supports the same filter syntax as Adblock Plus 0.7. And instead of displaying an error page this extension will notify you via info bar, similar to when a popup is blocked — you don’t leave the page you are currently viewing.