fix for framebuffer width and height when window hasn't been realized.

src/mesa/drivers/x11/xm_dd.c

-/* $Id: xm_dd.c,v 1.41 2002/10/30 20:24:47 brianp Exp $ */
+/* $Id: xm_dd.c,v 1.42 2003/01/16 19:10:46 alanh Exp $ */
 
 /*
  * Mesa 3-D graphics library
    unsigned int winwidth, winheight;
 #ifdef XFree86Server
    /* XFree86 GLX renderer */
-   winwidth = xmBuffer->frontbuffer->width;
-   winheight = xmBuffer->frontbuffer->height;
+   if (xmBuffer->frontbuffer->width > MAX_WIDTH ||
+       xmBuffer->frontbuffer->height > MAX_HEIGHT) {
+     winwidth = buffer->Width;
+     winheight = buffer->Height;
+   } else {
+     winwidth = xmBuffer->frontbuffer->width;
+     winheight = xmBuffer->frontbuffer->height;
+   }
 #else
    Window root;
    int winx, winy;