Xlib: drawing into window of other process

[baldo]

hi,

i'm looking for a way to draw calculation-results from multiple processes into one single window (processes might run on cluster later). i know there is a library called mpe (within mpich) solving this problem. unfortunately this library only provides very poor functionality and as far as i know only works within mpi (also non mpi-version planned).

i tried serveral toolkits (qt, fltk, ...) but couldn't find a solution. now i'm trying to do so using xlib directly (mpe does so) somehow like this:

- create 2 processes via fork()
- in process 1:

Display *dpy = XOpenDisplay(0);
Window w = XCreateSimpleWindow(dpy, DefaultRootWindow(dpy), 0, 0, 200, 100, 0, blackColor, blackColor);
XSelectInput(dpy, w, StructureNotifyMask);
XMapWindow(dpy, w);
GC gc = XCreateGC(dpy, w, 0, NIL);
XSetForeground(dpy, gc, whiteColor);
for(;;) {
  XEvent e;
  XNextEvent(dpy, &e);
  if (e.type == MapNotify)
    break;
  }
}
XDrawLine(dpy, w, gc, 10, 60, 180, 20); // works
XFlush(dpy);

-then passing w and gc to process 2 via shared memory (later via mpi?!?)
-in process 2:

Display *dpy = XOpenDisplay(0);
XDrawRectangle(dpy, w, gc, 10, 10, 20, 20); // does not take any effect
XFlush(dpy);

any solutions?

thx
baldo