* src/xdisp.c (syms_of_xdisp) <"scroll-minibuffer-conservatively">: New var

Fix bug#44070, which causes the minibuffer display to jump upon minor edit

(redisplay_window): Obey it.
* lisp/simple.el (end-of-buffer): Obey it.

* test/src/xdisp-tests.el (xdisp-tests--in-minibuffer): New macro,
extracted from `xdisp-tests--minibuffer-resizing`.
(xdisp-tests--minibuffer-resizing): Use it.
(xdisp-tests--minibuffer-scroll): New test.

1 files changed, 14 insertions, 3 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index 0e5dffbe007..cc499f33261 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -18820,6 +18820,7 @@ redisplay_window (Lisp_Object window, bool just_this_one_p)
 
   /* Try to scroll by specified few lines.  */
   if ((0 < scroll_conservatively
+       || (scroll_minibuffer_conservatively && MINI_WINDOW_P (w))
        || 0 < emacs_scroll_step
        || temp_scroll_step
        || NUMBERP (BVAR (current_buffer, scroll_up_aggressively))
@@ -18830,7 +18831,10 @@ redisplay_window (Lisp_Object window, bool just_this_one_p)
       /* The function returns -1 if new fonts were loaded, 1 if
          successful, 0 if not successful.  */
       int ss = try_scrolling (window, just_this_one_p,
-                              scroll_conservatively,
+                              ((scroll_minibuffer_conservatively
+                                && MINI_WINDOW_P (w))
+                               ? SCROLL_LIMIT + 1
+                               : scroll_conservatively),
                               emacs_scroll_step,
                               temp_scroll_step, last_line_misfit);
       switch (ss)
@@ -34538,7 +34542,14 @@ syms_of_xdisp (void)
 
   DEFSYM (Qredisplay_internal_xC_functionx, "redisplay_internal (C function)");
 
-  DEFVAR_BOOL("inhibit-message", inhibit_message,
+  DEFVAR_BOOL ("scroll-minibuffer-conservatively",
+               scroll_minibuffer_conservatively,
+               doc: /* Non-nil means scroll conservatively in minibuffer windows.
+When the value is nil, scrolling in minibuffer windows obeys the
+settings of `scroll-conservatively'.  */);
+  scroll_minibuffer_conservatively = true; /* bug#44070 */
+
+  DEFVAR_BOOL ("inhibit-message", inhibit_message,
               doc:  /* Non-nil means calls to `message' are not displayed.
 They are still logged to the *Messages* buffer.
 
@@ -34546,7 +34557,7 @@ Do NOT set this globally to a non-nil value, as doing that will
 disable messages everywhere, including in I-search and other
 places where they are necessary.  This variable is intended to
 be let-bound around code that needs to disable messages temporarily. */);
-  inhibit_message = 0;
+  inhibit_message = false;
 
   message_dolog_marker1 = Fmake_marker ();
   staticpro (&message_dolog_marker1);