Forum Discussion
When you close the window using a shortcut key, a shutdown dialog box will appear.
When closing certain applications, pressing Alt + F4 is supposed to close the current window, but occasionally it brings up the “Shut Down Windows” dialog box instead, leading to accidental shutdowns...
If that window isn't the application you're looking at (or if no application window is active), the command falls back to the desktop, which triggers the Shut Down dialog.