Hello, all--

I am working on some enhancements to LablTk, to bring it up to date with
Tk 8.4. One of the features I want to implement is validation for Entry
and Spinbox widgets (the latter being a new widget that I have added
already). It looks like this will require support module(s) in the
'builtin' directory ... the validation commands are somewhat like event
bindings, in that they use fields (with % substitutions in Tcl syntax)
and require registering callbacks; on the other hand, unlike event
bindings, but like Button and Menu commands, they are bound to the
widgets with configuration options rather than a standalone binding command.

So I need to understand more about those 'builtin' components. I'm sure
I can work out the answers myself, but it will take a lot of time, so
I'd greatly appreciate it if someone could answer at least these questions:

 * How are external support modules associated with modules generated
   from Widgets.src? If I introduce a new module(s), do I need to modify
   a Makefile, or are the dependencies all auto-detected? In the latter
   case, what do I need to do so that

     option ValidationCommand

   will work in a widget definition, where the ValidationCommand type is
   defined in an external module?

 * What do the prefixes 'builtin_', 'builtina_', 'builtinf_', and
   'builtini_' mean, and why do some of the modules in 'builtin' have
   these prefixes, while others have no prefix?
-- 
Matt Gushee
Englewood, CO, USA