gtk widgets interaction - from different applications/tasks

[Pedro Amaral Couto <pac_projects netcabo pt>]

 Is it possible a GTK application interact to other application widget?
 How?

---
 Eg:

 viewimage : application to show/view an image from file;
 paint     : painter ( something like Gimp, for eg )

 1- run "viewimage.exe myimg.png"; a Gtk_Window (view_window) contains a
Gtk_Image (view_image);
 2- run "paint"
 3- from "paint" window, select "brush" from "toolbar"
 4- paint "view_image" (a Gtk_Image from viewimage app) with "brush"
---

 This seems a strange thing to do (I've never seen an application doing
something similar ...), but I don't think it's impossible (shared
memory, sockets, reparent window, ...).

Regards.
  Pedro Amaral Couto