Block cmd w from closing xterm window on mac

After doing this at least twice in 24 hours I thought I better sort this out. You can block cmd w (close window) and assign it to something else to stop this from happening.

Goto System Preferences -> Keyboard -> Keyborad Shortcuts -> Application Shortcuts

Then Add (+)

Application = X11.app
Window = Close
Shortcut = Whatever you want I use cmd+shift+w

Danke.