FVWM: bug: XMapWindow/XUnmapWindow race condition

[Jindrich Makovicka]

Hello,
There is a problem with XMapWindow and XUnmapWindow handling - when they 
are called too fast one after another, the window just disappears. This 
is the cause of disappearing window in official binary builds of mozilla 
and probably also in new Adobe Reader 7.

Sample code triggering the bug is attached. The created window is 
visible for one second, then disappears forever. After uncommenting the 
delay between map and unmap, the window vanishes for 1 second, then 
appears again.

--
Jindrich Makovicka
#include <stdio.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <unistd.h>
Display *dpy;
Screen *scr;
Window root_win;
int scr_width, scr_height;
int depth;

XSizeHints hint;
XSetWindowAttributes attrib;

Window win;
int win_width, win_height;

int main(int argc, char **argv)
{
  XEvent ev;
  int i, j;
  int x;
  
  
  dpy = XOpenDisplay(":0.0");
  scr = DefaultScreenOfDisplay(dpy);
  root_win = RootWindowOfScreen(scr);
  scr_height = XHeightOfScreen(scr);
  scr_width = XWidthOfScreen(scr);
  depth = DefaultDepth(dpy, 0);

  win_width = 100;
  win_height = 100;

  win = XCreateWindow(dpy, root_win, 500, 500, win_width, win_height, 0, CopyFromParent, InputOutput,
                      CopyFromParent, 0, &attrib);
  XMapWindow(dpy, win);
  XFlush(dpy);
  sleep(1);
  
  XUnmapWindow(dpy, win);
  XFlush(dpy);
//  sleep(1); // uncomment to make it work
  XMapWindow(dpy, win);
  XFlush(dpy);

  sleep(5);

  XCloseDisplay(dpy);
  return 0;
}