Emacs Init: Define Command for Mouse Click

Define a Command Act on Mouse Clicked Point

To make the command act on mouse clicked point, you need to write a wrapper command that sets the position, then call the command you want.

For example, suppose the command you want is describe-char on clicked point. You write a wrapper, like this:

(defun xah-click-describe-char (Click)
  "Mouse click to `describe-char' at clicked point.
URL `http://xahlee.info/emacs/emacs/emacs_mouse_wheel_config.html'
Version: 2016-07-18"
  (interactive "e")
  (let ((xp (posn-point (event-start Click))))
    (goto-char xp)
    (describe-char xp)))

;; make right button show char info on clicked point
(global-set-key (kbd "<mouse-3>") 'xah-describe-char-on-click)

Define a Command for Cursor Point

When you bind a mouse button to a command, the command acts on the current cursor position, not clicked point.

;; make right button show char info (of current cursor position, not clicked point)
(global-set-key (kbd "<mouse-3>") 'describe-char)