xterm-mouse-mode

xterm-mouse-mode is a variable defined in `xt-mouse.el'.
Its value is

nil

Documentation:
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'.

You can customize this variable.