2 files changed, 52 insertions, 34 deletions

diff --git a/src/w32fns.c b/src/w32fns.c
index 8dca03265b7..311f9021c85 100644
--- a/src/w32fns.c
+++ b/src/w32fns.c
@@ -1677,6 +1677,12 @@ x_clear_under_internal_border (struct frame *f)
 }
 
 
+/**
+ * x_set_internal_border_width:
+ *
+ * Set width of frame F's internal border to ARG pixels.  ARG < 0 is
+ * treated like ARG = 0.
+ */
 void
 x_set_internal_border_width (struct frame *f, Lisp_Object arg, Lisp_Object oldval)
 {
@@ -1700,44 +1706,59 @@ x_set_internal_border_width (struct frame *f, Lisp_Object arg, Lisp_Object oldva
 }
 
 
+/**
+ * x_set_menu_bar_lines:
+ *
+ * Set number of lines of frame F's menu bar to VALUE.  An integer
+ * greater zero specifies 1 line and turns the menu bar on if it was off
+ * before.  Any other value specifies 0 lines and turns the menu bar off
+ * if it was on before.
+ */
 void
 x_set_menu_bar_lines (struct frame *f, Lisp_Object value, Lisp_Object oldval)
 {
-  int nlines;
-
   /* Right now, menu bars don't work properly in minibuf-only frames;
      most of the commands try to apply themselves to the minibuffer
-     frame itself, and get an error because you can't switch buffers
-     in or split the minibuffer window.  */
-  if (FRAME_MINIBUF_ONLY_P (f) || FRAME_PARENT_FRAME (f))
-    return;
+     frame itself, and get an error because you can't switch buffers in
+     or split the minibuffer window.  Child frames don't like menu bars
+     either.  */
+  if (!FRAME_MINIBUF_ONLY_P (f) && !FRAME_PARENT_FRAME (f))
+    {
+      boolean old = FRAME_EXTERNAL_MENU_BAR (f);
+      boolean new = (INTEGERP (value) && XINT (value) > 0) ? true : false;
 
-  if (INTEGERP (value))
-    nlines = XINT (value);
-  else
-    nlines = 0;
+      FRAME_MENU_BAR_LINES (f) = 0;
+      FRAME_MENU_BAR_HEIGHT (f) = 0;
 
-  FRAME_MENU_BAR_LINES (f) = 0;
-  FRAME_MENU_BAR_HEIGHT (f) = 0;
-  if (nlines)
-    FRAME_EXTERNAL_MENU_BAR (f) = 1;
-  else
-    {
-      if (FRAME_EXTERNAL_MENU_BAR (f) == 1)
-        free_frame_menubar (f);
-      FRAME_EXTERNAL_MENU_BAR (f) = 0;
+      if (old != new)
+        {
+          FRAME_EXTERNAL_MENU_BAR (f) = new;
 
-      /* Adjust the frame size so that the client (text) dimensions
-         remain the same.  This depends on FRAME_EXTERNAL_MENU_BAR being
-         set correctly.  Note that we resize twice: The first time upon
-         a request from the window manager who wants to keep the height
-         of the outer rectangle (including decorations) unchanged, and a
-         second time because we want to keep the height of the inner
-         rectangle (without the decorations unchanged).  */
-      adjust_frame_size (f, -1, -1, 2, true, Qmenu_bar_lines);
+          if (!old)
+            /* Make menu bar when there was none.  Emacs 25 waited until
+               the next redisplay for this to take effect.  */
+            set_frame_menubar (f, false, true);
+          else
+            {
+              /* Remove menu bar.  */
+              free_frame_menubar (f);
+
+              /* Adjust the frame size so that the client (text) dimensions
+                 remain the same.  Note that we resize twice: The first time
+                 upon a request from the window manager who wants to keep
+                 the height of the outer rectangle (including decorations)
+                 unchanged, and a second time because we want to keep the
+                 height of the inner rectangle (without the decorations
+                 unchanged).  */
+              adjust_frame_size (f, -1, -1, 2, false, Qmenu_bar_lines);
+            }
+
+          if (FRAME_W32_WINDOW (f))
+            x_clear_under_internal_border (f);
 
-      /* Not sure whether this is needed.  */
-      x_clear_under_internal_border (f);
+          /* Don't store anything but 1 or 0 in the parameter.  */
+          store_frame_param (f, Qmenu_bar_lines, make_number (new ? 1 : 0));
+        }
     }
 }
 
@@ -1820,7 +1841,7 @@ x_change_tool_bar_height (struct frame *f, int height)
      here.  */
   adjust_frame_glyphs (f);
   SET_FRAME_GARBAGED (f);
-  if (FRAME_X_WINDOW (f))
+  if (FRAME_W32_WINDOW (f))
     x_clear_under_internal_border (f);
 }
 
diff --git a/src/w32term.c b/src/w32term.c
index b3608accb34..a2537e204d8 100644
--- a/src/w32term.c
+++ b/src/w32term.c
@@ -6272,10 +6272,7 @@ x_set_window_size (struct frame *f, bool change_gravity,
 
   /* Get the height of the menu bar here.  It's used below to detect
      whether the menu bar is wrapped.  It's also used to specify the
-     third argument for AdjustWindowRect.  FRAME_EXTERNAL_MENU_BAR which
-     has been used before for that reason is unreliable because it only
-     specifies whether we _want_ a menu bar for this frame and not
-     whether this frame _has_ a menu bar.  See bug#22105.  */
+     third argument for AdjustWindowRect.  See bug#22105.  */
   info.cbSize = sizeof (info);
   info.rcBar.top = info.rcBar.bottom = 0;
   GetMenuBarInfo (FRAME_W32_WINDOW (f), 0xFFFFFFFD, 0, &info);