4 files changed, 108 insertions, 25 deletions

diff --git a/src/frame.c b/src/frame.c
index ecf175f4f99..4dd8bb18041 100644
--- a/src/frame.c
+++ b/src/frame.c
@@ -5943,6 +5943,7 @@ syms_of_frame (void)
   DEFSYM (Qxg_frame_set_char_size_1, "xg-frame-set-char-size-1");
   DEFSYM (Qxg_frame_set_char_size_2, "xg-frame-set-char-size-2");
   DEFSYM (Qxg_frame_set_char_size_3, "xg-frame-set-char-size-3");
+  DEFSYM (Qxg_frame_set_char_size_4, "xg-frame-set-char-size-4");
   DEFSYM (Qx_set_window_size_1, "x-set-window-size-1");
   DEFSYM (Qx_set_window_size_2, "x-set-window-size-2");
   DEFSYM (Qx_set_window_size_3, "x-set-window-size-3");
diff --git a/src/gtkutil.c b/src/gtkutil.c
index 5e7cf3d2114..e374bdbe037 100644
--- a/src/gtkutil.c
+++ b/src/gtkutil.c
@@ -941,9 +941,8 @@ xg_frame_resized (struct frame *f, int pixelwidth, int pixelheight)
     }
 }
 
-/* Resize the outer window of frame F after changing the height.
-   COLUMNS/ROWS is the size the edit area shall have after the resize.  */
-
+/** Resize the outer window of frame F.  WIDTH and HEIGHT are the new
+    pixel sizes of F's text area.  */
 void
 xg_frame_set_char_size (struct frame *f, int width, int height)
 {
@@ -954,6 +953,7 @@ xg_frame_set_char_size (struct frame *f, int width, int height)
   int totalheight
     = pixelheight + FRAME_TOOLBAR_HEIGHT (f) + FRAME_MENUBAR_HEIGHT (f);
   int totalwidth = pixelwidth + FRAME_TOOLBAR_WIDTH (f);
+  bool was_visible = false;
 
   if (FRAME_PIXEL_HEIGHT (f) == 0)
     return;
@@ -996,12 +996,35 @@ xg_frame_set_char_size (struct frame *f, int width, int height)
       gtk_window_resize (GTK_WINDOW (FRAME_GTK_OUTER_WIDGET (f)),
                          totalwidth, gheight);
     }
+  else if (FRAME_PARENT_FRAME (f) && FRAME_VISIBLE_P (f)
+           && EQ (x_gtk_resize_child_frames, Qhide))
+    {
+      was_visible = true;
+
+      if (totalwidth != gwidth || totalheight != gheight)
+        {
+          frame_size_history_add
+            (f, Qxg_frame_set_char_size_4, width, height,
+             list2i (totalwidth, totalheight));
+          block_input ();
+          gtk_widget_hide (FRAME_GTK_OUTER_WIDGET (f));
+          unblock_input ();
+
+          gtk_window_resize (GTK_WINDOW (FRAME_GTK_OUTER_WIDGET (f)),
+                             totalwidth, totalheight);
+
+          block_input ();
+          gtk_widget_show_all (FRAME_GTK_OUTER_WIDGET (f));
+          unblock_input ();
+
+          fullscreen = Qnil;
+        }
+    }
   else
     {
       frame_size_history_add
         (f, Qxg_frame_set_char_size_3, width, height,
          list2i (totalwidth, totalheight));
-
       gtk_window_resize (GTK_WINDOW (FRAME_GTK_OUTER_WIDGET (f)),
                          totalwidth, totalheight);
       fullscreen = Qnil;
@@ -1017,7 +1040,7 @@ xg_frame_set_char_size (struct frame *f, int width, int height)
      size as fast as possible.
      For unmapped windows, we can set rows/cols.  When
      the frame is mapped again we will (hopefully) get the correct size.  */
-  if (FRAME_VISIBLE_P (f))
+  if (FRAME_VISIBLE_P (f) && !was_visible)
     {
       /* Must call this to flush out events */
       (void)gtk_events_pending ();
diff --git a/src/xfns.c b/src/xfns.c
index afe1ceef81a..0fc553012bd 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -861,6 +861,12 @@ x_set_parent_frame (struct frame *f, Lisp_Object new_value, Lisp_Object old_valu
         (FRAME_X_DISPLAY (f), FRAME_OUTER_WINDOW (f),
          p ? FRAME_X_WINDOW (p) : DefaultRootWindow (FRAME_X_DISPLAY (f)),
          f->left_pos, f->top_pos);
+#ifdef USE_GTK
+      if (EQ (x_gtk_resize_child_frames, Qresize_mode))
+        gtk_container_set_resize_mode
+          (GTK_CONTAINER (FRAME_GTK_OUTER_WIDGET (f)),
+           p ? GTK_RESIZE_IMMEDIATE : GTK_RESIZE_QUEUE);
+#endif
       unblock_input ();
 
       fset_parent_frame (f, new_value);
@@ -4084,6 +4090,11 @@ This function is an internal primitive--use `make-frame' instead.  */)
       block_input ();
       XReparentWindow (FRAME_X_DISPLAY (f), FRAME_OUTER_WINDOW (f),
                        FRAME_X_WINDOW (p), f->left_pos, f->top_pos);
+#ifdef USE_GTK
+      if (EQ (x_gtk_resize_child_frames, Qresize_mode))
+        gtk_container_set_resize_mode
+          (GTK_CONTAINER (FRAME_GTK_OUTER_WIDGET (f)), GTK_RESIZE_IMMEDIATE);
+#endif
       unblock_input ();
     }
 
@@ -7742,6 +7753,22 @@ Note: Text drawn with the `x' font backend is shown with hollow boxes.  */)
 #endif  /* USE_GTK */
 #endif  /* USE_CAIRO */
 
+#ifdef USE_GTK
+#ifdef HAVE_GTK3
+DEFUN ("x-gtk-debug", Fx_gtk_debug, Sx_gtk_debug, 1, 1, 0,
+       doc: /* Toggle interactive GTK debugging.   */)
+  (Lisp_Object enable)
+{
+  gboolean enable_debug = !NILP (enable);
+
+  block_input ();
+  gtk_window_set_interactive_debugging (enable_debug);
+  unblock_input ();
+
+  return NILP (enable) ? Qnil : Qt;
+}
+#endif /* HAVE_GTK3 */
+#endif  /* USE_GTK */
 
 /***********************************************************************
                             Initialization
@@ -7810,6 +7837,8 @@ syms_of_xfns (void)
   DEFSYM (Qfont_parameter, "font-parameter");
   DEFSYM (Qmono, "mono");
   DEFSYM (Qassq_delete_all, "assq-delete-all");
+  DEFSYM (Qhide, "hide");
+  DEFSYM (Qresize_mode, "resize-mode");
 
 #ifdef USE_CAIRO
   DEFSYM (Qpdf, "pdf");
@@ -7986,6 +8015,28 @@ Otherwise use Emacs own tooltip implementation.
 When using Gtk+ tooltips, the tooltip face is not used.  */);
   x_gtk_use_system_tooltips = true;
 
+  DEFVAR_LISP ("x-gtk-resize-child-frames", x_gtk_resize_child_frames,
+    doc: /* If non-nil, resize child frames specially with GTK builds.
+If this is nil, resize child frames like any other frames.  This is the
+default and usually works with most desktops.  Some desktop environments
+(GNOME shell in particular when using the mutter window manager),
+however, may refuse to resize a child frame when Emacs is built with
+GTK3.  For those environments, the two settings below are provided.
+
+If this equals the symbol 'hide', Emacs temporarily hides the child
+frame during resizing.  This approach seems to work reliably, may
+however induce some flicker when the frame is made visible again.
+
+If this equals the symbol 'resize-mode', Emacs uses GTK's resize mode to
+always trigger an immediate resize of the child frame.  This method is
+deprecated by GTK and may not work in future versions of that toolkit.
+It also may freeze Emacs when used with other desktop environments.  It
+avoids, however, the unpleasent flicker induced by the hiding approach.
+
+This variable is considered a temporary workaround and will be hopefully
+eliminated in future versions of Emacs.  */);
+  x_gtk_resize_child_frames = Qnil;
+
   /* Tell Emacs about this window system.  */
   Fprovide (Qx, Qnil);
 
@@ -8101,4 +8152,9 @@ When using Gtk+ tooltips, the tooltip face is not used.  */);
   defsubr (&Sx_print_frames_dialog);
 #endif
 #endif
+#ifdef USE_GTK
+#ifdef HAVE_GTK3
+  defsubr (&Sx_gtk_debug);
+#endif
+#endif
 }
diff --git a/src/xterm.c b/src/xterm.c
index bda976fcbbd..44396955ed0 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -10608,26 +10608,29 @@ x_set_offset (struct frame *f, register int xoff, register int yoff, int change_
                modified_left, modified_top);
 #endif
 
-  x_sync_with_move (f, f->left_pos, f->top_pos,
-                    FRAME_DISPLAY_INFO (f)->wm_type == X_WMTYPE_UNKNOWN);
-
-  /* change_gravity is non-zero when this function is called from Lisp to
-     programmatically move a frame.  In that case, we call
-     x_check_expected_move to discover if we have a "Type A" or "Type B"
-     window manager, and, for a "Type A" window manager, adjust the position
-     of the frame.
-
-     We call x_check_expected_move if a programmatic move occurred, and
-     either the window manager type (A/B) is unknown or it is Type A but we
-     need to compute the top/left offset adjustment for this frame.  */
-
-  if (change_gravity != 0
-      && !FRAME_PARENT_FRAME (f)
-      && (FRAME_DISPLAY_INFO (f)->wm_type == X_WMTYPE_UNKNOWN
-          || (FRAME_DISPLAY_INFO (f)->wm_type == X_WMTYPE_A
-              && (FRAME_X_OUTPUT (f)->move_offset_left == 0
-                  && FRAME_X_OUTPUT (f)->move_offset_top == 0))))
-    x_check_expected_move (f, modified_left, modified_top);
+  /* 'x_sync_with_move' is too costly for dragging child frames.  */
+  if (!FRAME_PARENT_FRAME (f))
+    {
+      x_sync_with_move (f, f->left_pos, f->top_pos,
+                        FRAME_DISPLAY_INFO (f)->wm_type == X_WMTYPE_UNKNOWN);
+
+      /* change_gravity is non-zero when this function is called from Lisp to
+         programmatically move a frame.  In that case, we call
+         x_check_expected_move to discover if we have a "Type A" or "Type B"
+         window manager, and, for a "Type A" window manager, adjust the position
+         of the frame.
+
+         We call x_check_expected_move if a programmatic move occurred, and
+         either the window manager type (A/B) is unknown or it is Type A but we
+         need to compute the top/left offset adjustment for this frame.  */
+
+      if (change_gravity != 0
+          && (FRAME_DISPLAY_INFO (f)->wm_type == X_WMTYPE_UNKNOWN
+              || (FRAME_DISPLAY_INFO (f)->wm_type == X_WMTYPE_A
+                  && (FRAME_X_OUTPUT (f)->move_offset_left == 0
+                      && FRAME_X_OUTPUT (f)->move_offset_top == 0))))
+        x_check_expected_move (f, modified_left, modified_top);
+    }
 
   unblock_input ();
 }