The page contains a script, associated to the BODY tag that could open a new window when the page is loaded by the browser (i.e. a pop-up window). If this is the case, the page fails to satisfy the checkpoint.

Try to avoid opening new pop-up windows.

If opening new pop-up windows is a required behavior, add a "Close" button to the new window that would close the new window.

When the browser opens a pop-up window the environment in which the user is working changes. It changes because:

• some features of the browser itself in the new window may change. For example, the browser's buttons may be hidden completely, the geometry and position of the new window change, the new window is opened on top of the old one, or, other times it is opened below;
• even if it is not disabled, the "Back" button of the browser does not work, since in the new window there is no "URL history" (and no previous URL).
• for pop-up windows the change is even worse, since they appear without any explicit action from the user side (except for clicking on a link or typing a URL).

These factors, possibly combined together, amplify the possible difficulties experienced by visitors, especially those who are disabled or use disabling technologies. For example, if the new window is opened with the same size and position as the old one, on top of the old one, it might appear to a visitor as the same window. The visitor might interpret the fact that the Back button does not work as a bug of the browser (and might restart the browser) or a bug in the site (and might switch to another one).

For visually impaired visitors it is even worse: screen readers might not be able to notify the user that there is a new window. Screen magnifiers users might have a very hard time in guessing that there is a new window somewhere and where the new window is placed.

Therefore it is crucial that in general the visitor is told that a new window is being opened. Obviously the visitor should be told that before opening the window, which for pop-up windows is not a viable solution.

In all cases, the new window should contain a button that leads the visitor back to the page that has opened the window (or alternatively that closes it). These buttons will work also if the new window has disabled the standard browser buttons.