Now that increasingly fewer pages can be referred to in that way because they are rather applications not pages, is it possible for a web page to capture the user's session screen, including the desktop area or other applications outside of the browser? My dog wears a tinfoil hat and wants to know. I feel bad for not being able to answer that myself.

I’m gonna say no.

I agree with scasey.

However, if the webpage is dodgy, it could conceivably contain some malware capable of snapping a screenshot if user were to activate it.

Globally? Out of the browser's window? Have you seen that somewhere?

No, I haven't heard of such a thing, but I did say "conceivably."

Malware activated by clicking a dodgy link is not necessarily restricted to the browser window. The dodgy link could drop a screenshot application (or a key logger or whatever) onto the HDD, which in turn might do its thing and phone home with the result.

Mind you, I think it's a stretch to believe that a bad guy would be interested in a screenshot; the odds of catching, say, a financial spreadsheet open to the screen would be far too small. Bad guy would much more likely be interested in grabbing a copy of said spreadsheet from the home directory.

I don't believe a dodgy link could drop an application without the user noticing it. The browser would prompt for a destination directory for the download. And I don't believe the application would run by itself like some kind of robot.

On the subject of interest, I wasn't thinking about an unknown looking for something like a financial spreadsheet. I thought about someone trying to spy on someone else's life, say, what we do and whom we communicate with throughout the day.

Er, no.

https://www.google.com/search?client...opping+malware

Bad guys engineer bad things. That's how they become bad guys.

I'm gonna say: they don't need to. They can get to much more, and more interesting data on your machine directly, without having to resort to taking screenshots. It's also less data (plain text vs. image files) to push through the network.
Of course I'm just speculating; I allow my browser to use javascript only very sparingly and never by default, and feel reasonably safe. Because without javascript, 99.9% of the attack surface is gone. Really.

Well as other said, it's possible. Bad guys do bad things. I have seen one admin doing this, doing screen shot of current login user without the user noticing it and sending the capture to a network share. But it was W1nx..if it's possible in another OS why would it not be possible for Linux.

And was that through a web page?
Sounds more like it happened through remote access on a company's network?

yes it was through a company's network, web page hmm..yes it's possible