From: Gerd Möllmann <gerd@gnu.org>
Date: Tue, 12 Nov 2024 08:23:27 +0000 (+0100)
Subject: Fix a FIXME In redisplay_internal
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=5b8b9e0af0d6b631e5b36d2a2b2ea4d304e041b6;p=emacs.git

Fix a FIXME In redisplay_internal

* src/xdisp.c (redisplay_internal): Compare root frames before
setting the frame garbaged.

(cherry picked from commit 37cdf2897ad51f45a228c86f5f12feeb284673df)
---

diff --git a/src/xdisp.c b/src/xdisp.c
index 7c69302df90..00db1857774 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -17037,19 +17037,22 @@ redisplay_internal (void)
   if (face_change)
     windows_or_buffers_changed = 47;
 
-  /* FIXME: Can we do better for tty child frames?  It could be
-     a bit faster when we switch between child frames of the same
-     root frame.  OTOH, it's probably not a frequent use case.  */
+  struct frame *previous_frame;
   if ((FRAME_TERMCAP_P (sf) || FRAME_MSDOS_P (sf))
-      && FRAME_TTY (sf)->previous_frame != sf)
+      && (previous_frame = FRAME_TTY (sf)->previous_frame,
+	  previous_frame != sf))
     {
-      /* Since frames on a single ASCII terminal share the same
-	 display area, displaying a different frame means redisplay
-	 the whole thing.  */
-      SET_FRAME_GARBAGED (sf);
+      if (previous_frame == NULL
+	  || root_frame (previous_frame) != root_frame (sf))
+	{
+	  /* Since frames on a single terminal share the same display
+	     area, displaying a different frame means redisplay the
+	     whole thing.  */
+	  SET_FRAME_GARBAGED (sf);
 #if !defined DOS_NT && !defined HAVE_ANDROID
-      set_tty_color_mode (FRAME_TTY (sf), sf);
+	  set_tty_color_mode (FRAME_TTY (sf), sf);
 #endif
+	}
       FRAME_TTY (sf)->previous_frame = sf;
     }