Backport fix for Bug#2423 from trunk.

* dispextern.h (TRY_WINDOW_CHECK_MARGINS)
(TRY_WINDOW_IGNORE_FONTS_CHANGE): New defines.

* xdisp.c (try_window): Change arg from CHECK_MARGINS to FLAGS.
Don't abort with fonts change if TRY_WINDOW_IGNORE_FONTS_CHANGE is
set in FLAGS.  Callers with non-zero CHECK_MARGINS changed to use
TRY_WINDOW_CHECK_MARGINS.

* xfns.c (Fx_show_tip): Undo last change.  Call try_window with
TRY_WINDOW_IGNORE_FONTS_CHANGE (Bug#2423).

4 files changed, 26 insertions, 7 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index a16e35df108..1e084a4bc3a 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,16 @@
+2010-11-04  YAMAMOTO Mitsuharu  <mituharu@math.s.chiba-u.ac.jp>
+
+	* dispextern.h (TRY_WINDOW_CHECK_MARGINS)
+	(TRY_WINDOW_IGNORE_FONTS_CHANGE): New defines.
+
+	* xdisp.c (try_window): Change arg from CHECK_MARGINS to FLAGS.
+	Don't abort with fonts change if TRY_WINDOW_IGNORE_FONTS_CHANGE is
+	set in FLAGS.  Callers with non-zero CHECK_MARGINS changed to use
+	TRY_WINDOW_CHECK_MARGINS.
+
+	* xfns.c (Fx_show_tip): Undo last change.  Call try_window with
+	TRY_WINDOW_IGNORE_FONTS_CHANGE (Bug#2423).
+
 2010-11-04  Jan Djärv  <jan.h.d@swipnet.se>
 
 	* xfns.c (x_real_positions): Only use _NET_FRAME_EXTENTS if our
diff --git a/src/dispextern.h b/src/dispextern.h
index ca91c5b6812..bc34aec2dd5 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -2841,6 +2841,10 @@ extern int x_intersect_rectangles P_ ((XRectangle *, XRectangle *,
 				       XRectangle *));
 #endif
 
+/* Flags passed to try_window.  */
+#define TRY_WINDOW_CHECK_MARGINS	(1 << 0)
+#define TRY_WINDOW_IGNORE_FONTS_CHANGE	(1 << 1)
+
 /* Defined in fringe.c */
 
 int lookup_fringe_bitmap (Lisp_Object);
diff --git a/src/xdisp.c b/src/xdisp.c
index 59e38e440e4..a416c8ff435 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -13577,7 +13577,7 @@ redisplay_window (window, just_this_one_p)
 	       = try_window_reusing_current_matrix (w)))
 	{
 	  IF_DEBUG (debug_method_add (w, "1"));
-	  if (try_window (window, startp, 1) < 0)
+	  if (try_window (window, startp, TRY_WINDOW_CHECK_MARGINS) < 0)
 	    /* -1 means we need to scroll.
 	       0 means we need new matrices, but fonts_changed_p
 	       is set in that case, so we will detect it below.  */
@@ -13936,13 +13936,15 @@ redisplay_window (window, just_this_one_p)
    Value is 1 if successful.  It is zero if fonts were loaded during
    redisplay which makes re-adjusting glyph matrices necessary, and -1
    if point would appear in the scroll margins.
-   (We check that only if CHECK_MARGINS is nonzero.  */
+   (We check the former only if TRY_WINDOW_IGNORE_FONTS_CHANGE is
+   unset in FLAGS, and the latter only if TRY_WINDOW_CHECK_MARGINS is
+   set in FLAGS.)  */
 
 int
-try_window (window, pos, check_margins)
+try_window (window, pos, flags)
      Lisp_Object window;
      struct text_pos pos;
-     int check_margins;
+     int flags;
 {
   struct window *w = XWINDOW (window);
   struct it it;
@@ -13964,12 +13966,12 @@ try_window (window, pos, check_margins)
     {
       if (display_line (&it))
 	last_text_row = it.glyph_row - 1;
-      if (fonts_changed_p)
+      if (fonts_changed_p && !(flags & TRY_WINDOW_IGNORE_FONTS_CHANGE))
 	return 0;
     }
 
   /* Don't let the cursor end in the scroll margins.  */
-  if (check_margins
+  if ((flags & TRY_WINDOW_CHECK_MARGINS)
       && !MINI_WINDOW_P (w))
     {
       int this_scroll_margin;
diff --git a/src/xfns.c b/src/xfns.c
index 635264ea862..b65323f199f 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -5224,7 +5224,7 @@ Text larger than the specified size is clipped.  */)
   clear_glyph_matrix (w->desired_matrix);
   clear_glyph_matrix (w->current_matrix);
   SET_TEXT_POS (pos, BEGV, BEGV_BYTE);
-  try_window (FRAME_ROOT_WINDOW (f), pos, 0);
+  try_window (FRAME_ROOT_WINDOW (f), pos, TRY_WINDOW_IGNORE_FONTS_CHANGE);
 
   /* Compute width and height of the tooltip.  */
   width = height = 0;