Created attachment 165895 [details]
example to reproduce bug

There are actually two bugs here, one in mutter and one in gnome-shell. The gnome-shell one is bug 642221.

Created attachment 182963 [details] [review]
Fix initial setting of _NET_WM_STATE on new windows

When reload_net_wm_state() is called at startup to read the initial
value of _NET_WM_STATE, it was calling recalc_window_type(), but not
recalc_features(), which meant that, eg, meta->skip_taskbar would
never get initialized from meta->wm_state_skip_taskbar, which meant
that next time mutter went to update the window's _NET_WM_STATE, it
would overwrite the app-specified initial values. Fix that.

(In metacity, this bug is masked by the fact that recalc_features()
gets called when reading the intial value of WM_NORMAL_HINTS, which
comes after _NET_WM_STATE in metacity's prop_hooks_table. In mutter,
the table got reordered at some point, exposing the bug.)

Review of attachment 182963 [details] [review]:

Hmm, will cause:

  /* FIXME:
   * Lame workaround for recalc_window_features
   * being used overzealously. The fix is to
   * only recalc_window_features when something
   * has actually changed.
   */
  if (window->constructing                               ||
      old_has_close_func != window->has_close_func       ||
      old_has_minimize_func != window->has_minimize_func ||
      old_has_move_func != window->has_move_func         ||
      old_has_resize_func != window->has_resize_func     ||
      old_has_shade_func != window->has_shade_func       ||
      old_always_sticky != window->always_sticky)
    set_allowed_actions_hint (window);

to lamely set the allowed actions hint an extra time for each window, but I guess that's another problem for another day.

Attachment 182963 [details] pushed as 6c4a283 - Fix initial setting of _NET_WM_STATE on new windows