window-x11.c: Handle a special case for sending a ConfigureNotify

event.

Windows tiled to the right or bottom-right corner were getting
skipped if their window geometry already matched the tiled size,
since with northwest gravity, the client window position wasn't
changing either (relative to the frame window).

Fixes #705
Fixes #659

Thanks @PCVFaust for help troubleshooting this.

src/x11/window-x11.c

@@ -1436,14 +1436,27 @@ meta_window_x11_move_resize_internal (MetaWindow                *window,
          priv->border_width != 0))
     need_configure_notify = TRUE;
 
-  /* We must send configure notify if we move but don't resize, since
-   * the client window may not get a real event
+  /* When tiling a window, the frame sizes changes - which edges depend on
+   * the tile direction. For every direction but META_TILE_RIGHT and
+   * META_TILE_LRC (lower-right-corner), the client position needs to be
+   * shifted in at least one direction relative to the frame window, and
+   * will need to tell the client window about it.
    */
   if ((need_move_client || need_move_frame) &&
       !(need_resize_client || need_resize_frame) &&
       window->type != META_WINDOW_TOOLTIP)
     need_configure_notify = TRUE;
 
+  /* For META_TILE_RIGHT and META_TILE_LRC, the right border and
+   * bottom border (for lrc) are removed, but the client size may not
+   * change, if it was already the tiled size. The client position
+   * won't need to change either, from the frame's upper-left-corner,
+   * so the window may not be notified.
+   */
+
+  if (need_resize_frame && !need_resize_client && window->type != META_WINDOW_TOOLTIP)
+    need_configure_notify = TRUE;
+
   /* MapRequest events with a PPosition or UPosition hint with a frame
    * are moved by mutter without resizing; send a configure notify
    * in such cases.  See #322840.  (Note that window->constructing is