Mockup builder

[Gabriele Greco <gabriele greco darts it>]

It does exist such a thing for GTK?

I mean not an interface builder like glade but something that let you 
create simple mockups to be used in the analysis phase of the project.

The problem with a GLADE mockup is that I cannot give for instance any 
viable hint of the CONTENTS of lists and trees (it's not fast at all to 
populate complex treeviews that holds images, text and widgets).

For instance Microsoft Visio has a mockup builder, that is in fact 
something like a vector graphics program. Very different as concept from 
an interface builder.

Just wondering if there is a GUI tool to do such tasks. The target is to 
be able to assign the design phase of the interface to a person more 
involved with graphics than to assign this task to a programmer.

Bye,
 Gabry