Fix window scrolling on TTY frames when there's no mode line

* src/window.c (window_internal_height): Remove tests for
next, prev, and parent pointers, as they are unrelated to
whether a window has a mode line.  (Bug#33363)

1 files changed, 8 insertions, 12 deletions

diff --git a/src/window.c b/src/window.c
index 9026a7b5f2a..9cde2c5ecc4 100644
--- a/src/window.c
+++ b/src/window.c
@@ -4934,25 +4934,21 @@ window_wants_header_line (struct window *w)
           : 0);
 }
 
-/* Return number of lines of text (not counting mode lines) in W.  */
+/* Return number of lines of text in window W, not counting the mode
+   line and header line, if any.  Do NOT use this for windows on GUI
+   frames; use window_body_height instead.  This function is only for
+   windows on TTY frames, where it is much more efficient.  */
 
 int
 window_internal_height (struct window *w)
 {
   int ht = w->total_lines;
 
-  if (!MINI_WINDOW_P (w))
-    {
-      if (!NILP (w->parent)
-          || WINDOWP (w->contents)
-          || !NILP (w->next)
-          || !NILP (w->prev)
-          || window_wants_mode_line (w))
-        --ht;
+  if (window_wants_mode_line (w))
+    --ht;
 
-      if (window_wants_header_line (w))
-        --ht;
-    }
+  if (window_wants_header_line (w))
+    --ht;
 
   return ht;
 }