Une version qui marche

Apres quelques tests voici une version qui fonctionne:

#include <stdlib.h>
#include <assert.h>
#include <Xlib.h>
#include <Imlib2.h>

...

int
main (int argc, char **argv)
{

XEvent ev;

disp = XOpenDisplay (NULL);
assert (disp != NULL);

vis = DefaultVisual (disp, DefaultScreen (disp));
depth = DefaultDepth (disp, DefaultScreen (disp));
cm = DefaultColormap (disp, DefaultScreen (disp));

win = XCreateSimpleWindow (disp, DefaultRootWindow (disp),
0, 0, windowWidth, windowHeight, 0, 0, 0);

XSelectInput (disp, win,
KeyPressMask | ButtonPressMask | StructureNotifyMask |
ExposureMask);

XMapWindow (disp, win);

imlib_context_set_display (disp);
imlib_context_set_visual (vis);
imlib_context_set_colormap (cm);
imlib_context_set_drawable (win);

image = imlib_load_image ("test.jpg");
redrawWindow ();

for (;;) {

XNextEvent (disp, &ev);
switch (ev.type)
{
case KeyPress:
case ButtonPress:
XCloseDisplay (disp);
exit (EXIT_SUCCESS);

case Expose:
if (ev.xexpose.count == 0)
updateWindow (ev.xexpose.x, ev.xexpose.y, ev.xexpose.width, ev.xexpose.height);
break;

case ConfigureNotify:
windowWidth = ev.xconfigure.width;
windowHeight = ev.xconfigure.height;
redrawWindow ();
break;
}
}
return 0;
}

#include <stdlib.h>
#include <assert.h>
#include <Xlib.h>

#include <Imlib2.h>

int
main (int argc, char **argv)
{

XEvent ev;

disp = XOpenDisplay (NULL);
assert (disp != NULL);

vis = DefaultVisual (disp, DefaultScreen (disp));
depth = DefaultDepth (disp, DefaultScreen (disp));
cm = DefaultColormap (disp, DefaultScreen (disp));

win = XCreateSimpleWindow (disp, DefaultRootWindow (disp),
0, 0, windowWidth, windowHeight, 0, 0, 0);

XSelectInput (disp, win,
KeyPressMask | ButtonPressMask | StructureNotifyMask |
ExposureMask);

XMapWindow (disp, win);

imlib_context_set_display (disp);
imlib_context_set_visual (vis);
imlib_context_set_colormap (cm);
imlib_context_set_drawable (win);

image = imlib_load_image ("test.jpg");
redrawWindow ();

for (;;) {

XNextEvent (disp, &ev);
switch (ev.type)
{
case KeyPress:
case ButtonPress:
XCloseDisplay (disp);
exit (EXIT_SUCCESS);

case Expose:
if (ev.xexpose.count == 0)
updateWindow (ev.xexpose.x, ev.xexpose.y, ev.xexpose.width, ev.xexpose.height);
break;

case ConfigureNotify:
windowWidth = ev.xconfigure.width;
windowHeight = ev.xconfigure.height;
redrawWindow ();
break;
}
}
return 0;
}

Pour expliquer ton probleme je pense que quand tu redirige les evenements resize il doit y a avoir deux trois trucs a faire pour avertir
la fenetre (win) de se changement de taille.