Hidden close window button

[greg]

Did you know there is a hidden close button on windows? Double-click the top left corner to close one! This is left over from Windows 3.1

"Window decorations on Windows 3.1 had no close button, so they used to let you double-click the menu button to close a window. When Windows 95 came along, they added a close button, but they kept the double-clicking behaviour. The ability to close a window by double-clicking the menu button has lasted right up until Vista; apparently Microsoft tried to take it out in the beta, but so many users complained that they left it in in the end."
https://blogs.gnome.org/metacity/2008/1 ... -to-close/