1.3.7 Pop-up windows
Pop-up windows are browser windows that pop-up in front of (or behind) the main window. They are often smaller than the main window.
They have two primary uses:
to provide extra information about something which doesn't need a whole page
to advertise another site or product.
The main window remains, so you can go back to it by closing the pop-up in one of these ways
use the close button if it has one
use the ‘X’ button in the top right corner of the pop-up menu.