What are these called

I am interested in creating a window that displays over the website, and grays out the background w开发者_JAVA技巧hen a form is processing a credit card transaction. The window will include a spinner and I want to make sure the spinner does not lock when the processing is taking place. What are these windows called and where would you suggest I obtain information on how to develop this?

Modal popup? Standby popup?

The Ajax control in asp.net to do this is called an UpdateProgress. I think that's a lousy name, though.