Hi!
If we don't have to follow what GNU Emacs is doing anyway, let's just
change behavior of {beginning,end}-of-buffer to this instead of
implementing a useless mode:
Index: basic.c
===================================================================
RCS file: /cvs/src/usr.bin/mg/basic.c,v
retrieving revision 1.48
diff -u -p -r1.48 basic.c
--- basic.c 3 Jun 2019 16:26:30 -0000 1.48
+++ basic.c 11 Jun 2019 15:15:15 -0000
@@ -124,7 +124,8 @@ forwchar(int f, int n)
int
gotobob(int f, int n)
{
- (void) setmark(f, n);
+ if (!curwp->w_markp)
+ (void) setmark(f, n);
curwp->w_dotp = bfirstlp(curbp);
curwp->w_doto = 0;
curwp->w_rflag |= WFFULL;
@@ -150,7 +151,8 @@ gotoeob(int f, int n)
int ln;
struct line *lp;
- (void) setmark(f, n);
+ if (!curwp->w_markp)
+ (void) setmark(f, n);
curwp->w_dotp = blastlp(curbp);
curwp->w_doto = llength(curwp->w_dotp);
curwp->w_dotline = curwp->w_bufp->b_lines;
Index: mg.1
===================================================================
RCS file: /cvs/src/usr.bin/mg/mg.1,v
retrieving revision 1.114
diff -u -p -r1.114 mg.1
--- mg.1 6 Jun 2019 18:17:34 -0000 1.114
+++ mg.1 11 Jun 2019 15:15:15 -0000
@@ -1,7 +1,7 @@
.\" $OpenBSD: mg.1,v 1.114 2019/06/06 18:17:34 jmc Exp $
.\" This file is in the public domain.
.\"
-.Dd $Mdocdate: June 6 2019 $
+.Dd $Mdocdate: June 11 2019 $
.Dt MG 1
.Os
.Sh NAME
@@ -408,6 +408,7 @@ Move cursor to the top of the buffer.
A numeric argument
.Va n
will move n/10th of the way from the top.
+Set mark at previous position if mark is not set.
.It beginning-of-line
Move cursor to the beginning of the line.
.It blink-and-insert
@@ -532,6 +533,7 @@ Move cursor to the end of the buffer.
A numeric argument
.Va n
will move n/10th of the way from the end.
+Set mark at previous position if mark is not set.
.It end-of-line
Move cursor to the end of the line.
.It enlarge-window
Index: region.c
===================================================================
RCS file: /cvs/src/usr.bin/mg/region.c,v
retrieving revision 1.37
diff -u -p -r1.37 region.c
--- region.c 9 Sep 2016 06:05:51 -0000 1.37
+++ region.c 11 Jun 2019 15:15:15 -0000
@@ -405,6 +405,7 @@ markbuffer(int f, int n)
{
if (gotoeob(f,n) == FALSE)
return (FALSE);
+ (void) clearmark(f, n);
if (gotobob(f,n) == FALSE)
return (FALSE);
return (TRUE);
