Outline mode : to show hierarchy of files

http://www.la.utexas.edu/lab/software/user/gnu/xemacs/xemacs_23.html#SEC182
http://www.xemacs.org/Documentation/packages/html/edit-utils_40.html#SEC56

-- update

Use outline-minor-mode command to activate it
Then :
M-x hide-other shows only methods proto
M-x show-all redisplay them