Toggle XTerm mouse mode.
With a prefix argument ARG, enable XTerm mouse mode if ARG is
positive, and disable it otherwise. If called from Lisp, enable
the mode if ARG is omitted or nil.
Turn it on to use Emacs mouse commands, and off to use xterm mouse commands.
This works in terminal emulators compatible with xterm. It only
works for simple uses of the mouse. Basically, only non-modified
single clicks are supported. When turned on, the normal xterm
mouse functionality for such clicks is still available by holding
down the SHIFT key while pressing the mouse button.
(fn &optional ARG)
Non-nil if Xterm-Mouse mode is enabled.
See the command `xterm-mouse-mode' for a description of this minor mode.
Setting this variable directly does not take effect;
either customize it (see the info node `Easy Customization')
or call the function `xterm-mouse-mode'.