I apologize if this isn't in the proper forum. Its mostly because I don't even know what language is used to code it.

Do any of you know how to do a popup window that actually "dims" the background and presents the popup content on the existing page? Or at least, it gives that impression ...

I've seen this on my bank website when I go idle for awhile. It dims the background and gives me a borderless box, front and center, asking me if I want to stay logged in. Borderless meaning its not a new "window" as far as I can tell.

I know there are numerous ways this can be designed, so if any of you have any examples you can point to for ideas that woul be great. Tips on hw to actually code it, with the various options (dim at 20%, 40%, etc) would be helpful too.

Thanks!

Basically it's Lightbox on a timer that is always reset to 0 on keypress or mouse movements

Not sure that you are using Jquery. However, here is an example which you may want to look into:

http://jquery.com/demo/thickbox/#sectionf-2