Top Secret Confidential Document

Clicking the button below starts a timeout: after seven seconds, this page will show an alert() dialog. If:

• you have two screens attached to your computer;
• you are using a browser which shows alerts in a separate dialog bog (like Chrome and Epiphany) rather than one which shows them as a widget inside the same window (like Firefox); and
• you position the browser window to be at the top left of your entire desktop

then try clicking the button below and immediately locking your screen. In Gnome 3.4 on Debian, at least, this window will be visible over the screen lock when the dialog pops up, as in this photograph.

(This is bug #67337.)