which-func-format
    
    which-func-format is a variable defined in `
which-func.el'.
Its value is shown 
below.
-   This variable may be risky if used as a file-local variable.
 
Documentation:
Format for displaying the function in the mode line.
You can customize this variable.
This variable was introduced, or its default value was changed, in
version 24.2 of Emacs.
Value: 
("["
 (:propertize which-func-current local-map
	      (keymap
	       (mode-line keymap
			  (mouse-3 . end-of-defun)
			  (mouse-2 .
				   #[nil "e\300=\203	 \301 \207~\207"
					 [1 narrow-to-defun]
					 2 nil nil])
			  (mouse-1 . beginning-of-defun)))
	      face which-func mouse-face mode-line-highlight help-echo "mouse-1: go to beginning\nmouse-2: toggle rest visibility\nmouse-3: go to end")
 "]")