General
Failure due to opening new windows when the user does not expect them. New windows take the focus away from what the user is reading or doing. This is fine when the user has interacted with a piece of User Interface and expects to get a new window, such as an options dialogue. The failure comes when pop-ups appear unexpectedly.
When a user navigates to a page, a new window appears over the existing user agent window, and the focus is moved to the new window.
A user clicks on a link, and a new window appears. The original link has no associated text saying that it will open a new window.
A user clicks on the body of a page and a new window appears. No indication that the area that was clicked has functionality is present.
A user clicks on undecorated text within the page and a new window appears. The page has no visible indication that the area is functional.