1 files changed, 23 insertions, 14 deletions

diff --git a/src/dispextern.h b/src/dispextern.h
index 15ff0227dba..9b899c2105f 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -916,22 +916,30 @@ extern struct glyph_row scratch_glyph_row;
       : 0)
 
 /* Return the current height of the mode line of window W.  If not
-   known from W's current glyph matrix, return a default based on the
-   height of the font of the face `modeline'.  */
-
-#define CURRENT_MODE_LINE_HEIGHT(W)                     \
-     (MATRIX_MODE_LINE_HEIGHT ((W)->current_matrix)     \
-      ? MATRIX_MODE_LINE_HEIGHT ((W)->current_matrix)   \
-      : estimate_mode_line_height (XFRAME ((W)->frame), MODE_LINE_FACE_ID))
+   known from current_mode_line_height, look at W's current glyph
+   matrix, or return a default based on the height of the font of the
+   face `mode-line'.  */
+
+#define CURRENT_MODE_LINE_HEIGHT(W)                             \
+     (current_mode_line_height >= 0                             \
+      ? current_mode_line_height                                \
+      : (MATRIX_MODE_LINE_HEIGHT ((W)->current_matrix)          \
+         ? MATRIX_MODE_LINE_HEIGHT ((W)->current_matrix)        \
+         : estimate_mode_line_height (XFRAME ((W)->frame),      \
+                                      MODE_LINE_FACE_ID)))
 
 /* Return the current height of the top line of window W.  If not
-   known from W's current glyph matrix, return an estimation based on
-   the height of the font of the face `top-line'.  */
-
-#define CURRENT_HEADER_LINE_HEIGHT(W)                                      \
-      (MATRIX_HEADER_LINE_HEIGHT ((W)->current_matrix)                     \
-      ? MATRIX_HEADER_LINE_HEIGHT ((W)->current_matrix)                    \
-      : estimate_mode_line_height (XFRAME ((W)->frame), HEADER_LINE_FACE_ID))
+   known from current_header_line_height, look at W's current glyph
+   matrix, or return an estimation based on the height of the font of
+   the face `header-line'.  */
+
+#define CURRENT_HEADER_LINE_HEIGHT(W)                           \
+      (current_header_line_height >= 0                          \
+       ? current_header_line_height                             \
+       : (MATRIX_HEADER_LINE_HEIGHT ((W)->current_matrix)       \
+          ? MATRIX_HEADER_LINE_HEIGHT ((W)->current_matrix)     \
+          : estimate_mode_line_height (XFRAME ((W)->frame),     \
+                                       HEADER_LINE_FACE_ID)))
 
 /* Return the height of the desired mode line of window W.  */
 
@@ -2154,6 +2162,7 @@ extern int redisplaying_p;
 extern Lisp_Object Vimage_types;
 extern void add_to_log P_ ((char *, Lisp_Object, Lisp_Object));
 extern int help_echo_showing_p;
+extern int current_mode_line_height, current_header_line_height;
 
 /* Defined in sysdep.c */