Disabling the default page layer

Hi all

If you go to www.microsoft.com and click the "Downloads & Trials" link on the right nav panel, a layer pops up with more info and the page behind it becomes disabled. The plesk control panel also does this. It is VERY useful but i have NO idea how they do this? I tried to create a layer of width and height 100% with a transparency of 90% to replicate this behaviour, it works, unless your page is more than one screen high/wide in which case its sizing and position is incorrect.

Can anyone help?

re: Disabling the default page layer

There's a name for that technique, I think, but it's done with javascript/aJax. I'd have to do some searching to find it but you should ask over there.