4 files changed, 102 insertions, 9 deletions

diff --git a/src/haikufns.c b/src/haikufns.c
index e0a65b499f4..67f79a31669 100644
--- a/src/haikufns.c
+++ b/src/haikufns.c
@@ -2330,6 +2330,10 @@ DEFUN ("x-show-tip", Fx_show_tip, Sx_show_tip, 1, 6, 0,
   int old_windows_or_buffers_changed = windows_or_buffers_changed;
   specpdl_ref count = SPECPDL_INDEX ();
   Lisp_Object window, size, tip_buf;
+  bool displayed;
+#ifdef ENABLE_CHECKING
+  struct glyph_row *row, *end;
+#endif
   AUTO_STRING (tip, " *tip*");
 
   specbind (Qinhibit_redisplay, Qt);
@@ -2558,7 +2562,26 @@ DEFUN ("x-show-tip", Fx_show_tip, Sx_show_tip, 1, 6, 0,
   clear_glyph_matrix (w->desired_matrix);
   clear_glyph_matrix (w->current_matrix);
   SET_TEXT_POS (pos, BEGV, BEGV_BYTE);
-  try_window (window, pos, TRY_WINDOW_IGNORE_FONTS_CHANGE);
+  displayed = try_window (window, pos, TRY_WINDOW_IGNORE_FONTS_CHANGE);
+
+  if (!displayed && NILP (Vx_max_tooltip_size))
+    {
+#ifdef ENABLE_CHECKING
+      row = w->desired_matrix->rows;
+      end = w->desired_matrix->rows + w->desired_matrix->nrows;
+
+      while (row < end)
+        {
+          if (!row->displays_text_p
+              || row->ends_at_zv_p)
+            break;
+          ++row;
+        }
+
+      eassert (row < end && row->ends_at_zv_p);
+#endif
+    }
+
   /* Calculate size of tooltip window.  */
   size = Fwindow_text_pixel_size (window, Qnil, Qnil, Qnil,
                                   make_fixnum (w->pixel_height), Qnil,
@@ -3179,7 +3202,7 @@ syms_of_haikufns (void)
 
   DEFVAR_LISP ("x-max-tooltip-size", Vx_max_tooltip_size,
                doc: /* SKIP: real doc in xfns.c.  */);
-  Vx_max_tooltip_size = Fcons (make_fixnum (80), make_fixnum (40));
+  Vx_max_tooltip_size = Qnil;
 
   DEFVAR_LISP ("x-cursor-fore-pixel", Vx_cursor_fore_pixel,
                doc: /* SKIP: real doc in xfns.c.  */);
diff --git a/src/nsfns.m b/src/nsfns.m
index 16174210669..b0b779bd41c 100644
--- a/src/nsfns.m
+++ b/src/nsfns.m
@@ -3210,7 +3210,8 @@ x_hide_tip (bool delete)
 
 DEFUN ("x-show-tip", Fx_show_tip, Sx_show_tip, 1, 6, 0,
        doc: /* SKIP: real doc in xfns.c.  */)
-     (Lisp_Object string, Lisp_Object frame, Lisp_Object parms, Lisp_Object timeout, Lisp_Object dx, Lisp_Object dy)
+  (Lisp_Object string, Lisp_Object frame, Lisp_Object parms,
+   Lisp_Object timeout, Lisp_Object dx, Lisp_Object dy)
 {
   int root_x, root_y;
   specpdl_ref count = SPECPDL_INDEX ();
@@ -3224,6 +3225,10 @@ DEFUN ("x-show-tip", Fx_show_tip, Sx_show_tip, 1, 6, 0,
   Lisp_Object window, size, tip_buf;
   char *str;
   NSWindow *nswindow;
+  bool displayed;
+#ifdef ENABLE_CHECKING
+  struct glyph_row *row, *end;
+#endif
 
   AUTO_STRING (tip, " *tip*");
 
@@ -3454,7 +3459,26 @@ DEFUN ("x-show-tip", Fx_show_tip, Sx_show_tip, 1, 6, 0,
       clear_glyph_matrix (w->desired_matrix);
       clear_glyph_matrix (w->current_matrix);
       SET_TEXT_POS (pos, BEGV, BEGV_BYTE);
-      try_window (window, pos, TRY_WINDOW_IGNORE_FONTS_CHANGE);
+      displayed = try_window (window, pos, TRY_WINDOW_IGNORE_FONTS_CHANGE);
+
+      if (!displayed && NILP (Vx_max_tooltip_size))
+        {
+#ifdef ENABLE_CHECKING
+          row = w->desired_matrix->rows;
+          end = w->desired_matrix->rows + w->desired_matrix->nrows;
+
+          while (row < end)
+            {
+              if (!row->displays_text_p
+                  || row->ends_at_zv_p)
+                break;
+              ++row;
+            }
+
+          eassert (row < end && row->ends_at_zv_p);
+#endif
+        }
+
       /* Calculate size of tooltip window.  */
       size = Fwindow_text_pixel_size (window, Qnil, Qnil, Qnil,
                                       make_fixnum (w->pixel_height), Qnil,
@@ -3889,7 +3913,7 @@ Default is t.  */);
 
   DEFVAR_LISP ("x-max-tooltip-size", Vx_max_tooltip_size,
     doc: /* SKIP: real doc in xfns.c.  */);
-  Vx_max_tooltip_size = Fcons (make_fixnum (80), make_fixnum (40));
+  Vx_max_tooltip_size = Qnil;
 
   defsubr (&Sns_read_file_name);
   defsubr (&Sns_get_resource);
diff --git a/src/pgtkfns.c b/src/pgtkfns.c
index 5c43e5f3607..d998c3d938c 100644
--- a/src/pgtkfns.c
+++ b/src/pgtkfns.c
@@ -3130,6 +3130,10 @@ Text larger than the specified size is clipped.  */)
   int old_windows_or_buffers_changed = windows_or_buffers_changed;
   specpdl_ref count = SPECPDL_INDEX ();
   Lisp_Object window, size, tip_buf;
+  bool displayed;
+#ifdef ENABLE_CHECKING
+  struct glyph_row *row, *end;
+#endif
   AUTO_STRING (tip, " *tip*");
 
   specbind (Qinhibit_redisplay, Qt);
@@ -3334,7 +3338,26 @@ 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 (window, pos, TRY_WINDOW_IGNORE_FONTS_CHANGE);
+  displayed = try_window (window, pos, TRY_WINDOW_IGNORE_FONTS_CHANGE);
+
+  if (!displayed && NILP (Vx_max_tooltip_size))
+    {
+#ifdef ENABLE_CHECKING
+      row = w->desired_matrix->rows;
+      end = w->desired_matrix->rows + w->desired_matrix->nrows;
+
+      while (row < end)
+        {
+          if (!row->displays_text_p
+              || row->ends_at_zv_p)
+            break;
+          ++row;
+        }
+
+      eassert (row < end && row->ends_at_zv_p);
+#endif
+    }
+
   /* Calculate size of tooltip window.  */
   size = Fwindow_text_pixel_size (window, Qnil, Qnil, Qnil,
                                   make_fixnum (w->pixel_height), Qnil,
@@ -3924,7 +3947,7 @@ syms_of_pgtkfns (void)
 
   DEFVAR_LISP ("x-max-tooltip-size", Vx_max_tooltip_size,
                doc: /* SKIP: real doc in xfns.c.  */);
-  Vx_max_tooltip_size = Fcons (make_fixnum (80), make_fixnum (40));
+  Vx_max_tooltip_size = Qnil;
 
   DEFSYM (Qmono, "mono");
   DEFSYM (Qassq_delete_all, "assq-delete-all");
diff --git a/src/xfns.c b/src/xfns.c
index 44208ffd515..ce867c1619c 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -8623,6 +8623,10 @@ Text larger than the specified size is clipped.  */)
   Window child;
   XWindowAttributes child_attrs;
   int dest_x_return, dest_y_return;
+  bool displayed;
+#ifdef ENABLE_CHECKING
+  struct glyph_row *row, *end;
+#endif
   AUTO_STRING (tip, " *tip*");
 
   specbind (Qinhibit_redisplay, Qt);
@@ -8835,7 +8839,26 @@ 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 (window, pos, TRY_WINDOW_IGNORE_FONTS_CHANGE);
+  displayed = try_window (window, pos, TRY_WINDOW_IGNORE_FONTS_CHANGE);
+
+  if (!displayed && NILP (Vx_max_tooltip_size))
+    {
+#ifdef ENABLE_CHECKING
+      row = w->desired_matrix->rows;
+      end = w->desired_matrix->rows + w->desired_matrix->nrows;
+
+      while (row < end)
+        {
+          if (!row->displays_text_p
+              || row->ends_at_zv_p)
+            break;
+          ++row;
+        }
+
+      eassert (row < end && row->ends_at_zv_p);
+#endif
+    }
+
   /* Calculate size of tooltip window.  */
   size = Fwindow_text_pixel_size (window, Qnil, Qnil, Qnil,
                                   make_fixnum (w->pixel_height), Qnil,
@@ -9949,7 +9972,7 @@ or when you set the mouse color.  */);
   DEFVAR_LISP ("x-max-tooltip-size", Vx_max_tooltip_size,
     doc: /* Maximum size for tooltips.
 Value is a pair (COLUMNS . ROWS).  Text larger than this is clipped.  */);
-  Vx_max_tooltip_size = Fcons (make_fixnum (80), make_fixnum (40));
+  Vx_max_tooltip_size = Qnil;
 
   DEFVAR_LISP ("x-no-window-manager", Vx_no_window_manager,
     doc: /* Non-nil if no X window manager is in use.