How to block ads/pop-ups that gray out screen and show advertisment?

Question

I've seen quite a few webpages that use obtrusive advertising techniques such as this:

How can the signup form be blocked? I found using Adblock plus the form can be blocked, then the grayed out background can be blocked, but then the scroll bar on the side is no longer there.

It's like Adblock plus just stopped working. Here's another site that has ads that aren't being blocked http://walrusmagazine.com/articles/2010.09-environment-a-10-percent-world

Here's another example (takes some time for ad to load) http://www.howtogeek.com/121267/11-ways-to-make-your-lastpass-account-even-more-secure/

Yet another example of ads that aren't being blocked.

Solution

I don't have a "global solution" but what I do in these cases is (using firefox), I block the popup window, and the layer behind it (which actually is a semi-transparent 'curtain' in front of the content, covering it from user actions).
I use Ad-Block Plus with Element Hiding Helper - so I just open EHH (CTRL+SHIFT+F3), select the popup, block it, then open EHH again and block the semi-transparent "curtain".

Hope this helps!
(if you need more help, please post the site in question and I add screenshots for you)

Comments

[Admin]

Forgot to mention: what you do is right, the sidebar goes away if you block the wrong frame