diff -Nru metacity-3.18.3/debian/changelog metacity-3.18.3/debian/changelog
--- metacity-3.18.3/debian/changelog	2016-04-04 15:10:55.000000000 +0000
+++ metacity-3.18.3/debian/changelog	2016-04-13 14:33:16.000000000 +0000
@@ -1,3 +1,10 @@
+metacity (1:3.18.3-1ubuntu3) xenial; urgency=medium
+
+  * Backport upstream change (add_window_back_to_compositor.diff) to fix
+    windows getting hidden sometimes (LP: #1538111).
+
+ -- Dmitry Shachnev <mitya57@ubuntu.com>  Wed, 13 Apr 2016 17:31:12 +0300
+
 metacity (1:3.18.3-1ubuntu2) xenial; urgency=medium
 
   * Backport upstream change (compositor_root_background.diff) to fix root
diff -Nru metacity-3.18.3/debian/patches/add_window_back_to_compositor.diff metacity-3.18.3/debian/patches/add_window_back_to_compositor.diff
--- metacity-3.18.3/debian/patches/add_window_back_to_compositor.diff	1970-01-01 00:00:00.000000000 +0000
+++ metacity-3.18.3/debian/patches/add_window_back_to_compositor.diff	2016-04-13 14:31:08.000000000 +0000
@@ -0,0 +1,68 @@
+Description: compositor: add window back to compositor
+ Remove window from compositor when calling meta_window_free and
+ make sure to re-add window to the compositor when we re-create
+ MetaWindow on MapRequest.
+Origin: upstream, https://git.gnome.org/browse/metacity/commit/?id=04c99abaa2825c0c
+Bug: https://bugs.launchpad.net/bugs/1538111
+Last-Update: 2016-04-13
+
+--- a/src/compositor/compositor-xrender.c
++++ b/src/compositor/compositor-xrender.c
+@@ -2864,28 +2864,12 @@
+ {
+ #ifdef HAVE_COMPOSITE_EXTENSIONS
+   MetaCompositorXRender *xrc;
+-  MetaFrame *frame;
+   Window xwindow;
+ 
+   xrc = (MetaCompositorXRender *) compositor;
+-  frame = meta_window_get_frame (window);
+-  xwindow = None;
++  xwindow = meta_window_get_xwindow (window);
+ 
+-  if (frame)
+-    {
+-      xwindow = meta_frame_get_xwindow (frame);
+-    }
+-  else
+-    {
+-      /* FIXME: When an undecorated window is hidden this is called, but the
+-       * window does not get readded if it is subsequentally shown again. See:
+-       * http://bugzilla.gnome.org/show_bug.cgi?id=504876
+-       */
+-      /* xwindow = meta_window_get_xwindow (window); */
+-    }
+-
+-  if (xwindow != None)
+-    destroy_win (xrc->display, xwindow, FALSE);
++  destroy_win (xrc->display, xwindow, FALSE);
+ #endif
+ }
+ 
+--- a/src/core/display.c
++++ b/src/core/display.c
+@@ -2116,8 +2116,22 @@
+     case MapRequest:
+       if (window == NULL)
+         {
+-          window = meta_window_new (display, event->xmaprequest.window,
+-                                    FALSE);
++          Window xwindow;
++          XWindowAttributes attr;
++          int result;
++
++          xwindow = event->xmaprequest.window;
++          window = meta_window_new (display, xwindow, FALSE);
++
++          meta_error_trap_push (display);
++          result = XGetWindowAttributes (display->xdisplay, xwindow, &attr);
++          meta_error_trap_pop (display, TRUE);
++
++          if (result != 0)
++            {
++              meta_compositor_add_window (display->compositor, window,
++                                          xwindow, &attr);
++            }
+         }
+       /* if frame was receiver it's some malicious send event or something */
+       else if (!frame_was_receiver && window)
diff -Nru metacity-3.18.3/debian/patches/series metacity-3.18.3/debian/patches/series
--- metacity-3.18.3/debian/patches/series	2016-04-04 15:08:30.000000000 +0000
+++ metacity-3.18.3/debian/patches/series	2016-04-13 14:28:20.000000000 +0000
@@ -1 +1,2 @@
 compositor_root_background.diff
+add_window_back_to_compositor.diff