Hi kenny, et al.,
I was just updating the cells-gtk documentation. I am wondering whether I answered this question about using :initform with c? versus c-in correctly,
Q: What is the difference between using c-in and c? in a slot's :initform ? A: The usual semantics of :initform do not apply when :initform is given a c? rule. Instead of just setting the value at initialization, when c? is used, the value of the slot is checked and updated using the rule throughout program execution.
If you have the time, take a look at the answer to "What is Cells?" too. See: http://common-lisp.net/project/cells-gtk/faq.html
BTW, I will soon be rolling out some new capabilities with cells-gtk, including GtkDrawingArea, and bindings for the GDK primitives for drawing. I hope to have a demo that presents a graph and uses cells to update the edges as the user drags the nodes around.
I also have a cells-gtk "lisp listener" (or, more usefully, some custom command shell) in the works.