small GTK application interacting via network

[Stefano Galli <stegalli tiscali it>]

Hello everyone
i'm trying to write a small application to control a robot swarm
it takes a cell map from a file, draws the map using a gtk_table where 
each cell is filled with a colored pixmap. Each cell represents a 
portion of space where a robot can or cannot stand.
What i am not being able to do is changing the map!
Through tcp/ip connection i can modify the data structure representing 
each robot, but i do not know how to program the "repaint" of the map 
after a robot changes its position. It would be enough to change the 
pixmap associated to a certain position, but i do not know what to do!
Any idea?
Thanks anyway!

Stefano