[AD] Menus and Callbacks

[Dustin Dettmer <dustin@xxxxxxxxxx>]

> typedef struct MENU
> 
>    char *text;          - the text to display for
the menu item
>    int (*proc)(void);   - called when the menu item
is clicked
>    struct MENU *child;  - nested child menu
>    int flags;           - disabled or checked state
>    void *dp;            - pointer to any data you
need

>    Structure used to hold an entry of a menu. Read
chapter "GUI routines",
>    section "GUI menus" for a description on how to
obtain/use this structure.

Wouldnt it make sense for proc to get a copy of dp? 
The docs mention that dp is free for you to use, but
you cant.  Not passing dp to proc means that all menus
created using allegro's menuing system *must* be of
static length.  Static length menus are rather
undesirable imho.

I ran into this issue creating an editor that requires
an arbitrary amount of objects that the user can add,
remove and modify.  Upon trying to make a submenu with
a list of each object for modifying, I realised it was
impossible and in the end used a hackish callback
system which defined 300+ extra functions and put a
limit on the amount of objects the editor can handle
(300).  This problem could very easily be avoided if
proc was handed a copy of dp, so that the callback
function could 'know' which menu option called it.