If you’ve used XFCE4 Terminal as a terminal emulator on the desktop you may have noticed an odd behavior. Every so often a tab will inexplicably close while you’re using it or floating the mouse pointer by it on the desktop.
As it turns out this is a middle mouse button click to close. In my case it happens when I’m using the track pad. Or not using the track pad, as the case may be, and instead nailing it with my palms while typing.
At one point the setting was stored in ~/.config/Terminal/terminalrc and on some older installations this may still be the case. On the current (through updates) Ubuntu install that I’m running it’s located in ~/.config/xfce4/terminal/terminalrc and in either case the option in question is MiscTabCloseMiddleClick=TRUE which needs to be changed to MiscTabCloseMiddleClick=FALSE
Hopefully this will save you from the headache of having your work or connection unexpectedly disappear!