gEDA-dev: configurable pcb toolbars

[DJ Delorie]

I'm working on adding some of the GUI fluff to the lesstif interface
that's already there for the Gtk interface.  The current task is
toolbars, to get back the sidebar functionality.

Of course, the core code is more flexible than the "minimum" required
for that.  You can define multiple toolbars, attach them to any side
of the work area, and have them to anything (much like the menus,
which I'm copying code from).

This leads me to a look-and-feel issue, since Motif doesn't have
toolbars per se and thus no style guide for them.  Each "button" could
(once I write code for it), allow for multiple appearance changes:

* shadows can be "in" or "out" or "none"

* the icon can change

* the border can change

* the background color can change

The flags driving such changes are the same as used for menus:

* A sense of when the button is "active" (else it's greyed out)

* A sense of when the button is "checked" (such as the current layer)

We also still have the issue of making a layer current vs making a
layer visible.

Ideas?