GUI programming vs encapsulation

[Daniel Haude <dunno stoptrick com>]

Hello list,

as my Glade/GTK project is growing larger, I find myself confronted with 
code organization issues. I have all my callbacks in a single file, but 
of course there are groups of related widgets that logically go together 
(say, the widgets inside a top-level dialog window). Also the widgets of 
one dialog only need to know about each other, but not about widgets in 
other windows.

The issue is how to separate these things logically other than just 
splitting up the source code in comment-separated chunks.

1. Separate source files for each dialog.
   -> unpractical because this is a single Glade project, and Glade 
only writes single source files.

2. Storing information about widgets (i.e., pointers to widgets) inside 
the parent top-level widget using the G_OBJECT methods 
(g_object_set_data() and friends), and finding the widget with the 
lookup_widget() funcion supplied with Glade
   -> I somehow don't like it. I like mean, lean, and fast programs, 
and the mere thought that each push of a button or movement of a slider 
generates an avalanche of hash lookups gives me ulcers, and it litters 
the code with "magic" lookup key strings.

3. For each widget, declare a global pointer variable, a "create" and a 
"delete" callback. In the create callback I set the global variable to 
the pointer to the widget, and in the delete callback I set the global 
variable to NULL so that other parts of the program know that this 
widget doesn't exist any more.
   -> No encapsulation and more callbacks just to set/unset global 
variables.

Currently I'm using a mixture of 2. and 3. (depending on how I feel that 
day), but leaning towards 3. without much passion.

So how do you guys deal with this problem? I guess there is no real way 
out of having all the callbacks spread out in this "flat" fashion 
because from the C program's point of view there's no telling in what 
order they might be called. Is writing unwieldy spaghetti code a 
necessary part of GUI programming, or have I missed some important point?

Thanks,
--Daniel