Fix bug in redisplay: when variables that affect display (e.g.

truncate-lines) are changed, the window start marks must be erased.
Otherwise, the old start marks are used, and with the new display
variables in effect, these marks could cause point to be left
offscreen, or even force all of the buffer's text to be offscreen!

diff --git a/v7/src/edwin/bufwin.scm b/v7/src/edwin/bufwin.scm
index 12da7cc3562fde89bd31920fe9cd4ba3dade0e47..ec1d18f095ebcf3f08ee7e8b0057eec94eb507b9 100644 (file)
--- a/v7/src/edwin/bufwin.scm
+++ b/v7/src/edwin/bufwin.scm
@@ -1,8 +1,8 @@
 ;;; -*-Scheme-*-
 ;;;
-;;;    $Id: bufwin.scm,v 1.303 1994/09/08 20:34:04 adams Exp $
+;;;    $Id: bufwin.scm,v 1.304 1995/02/16 22:45:37 cph Exp $
 ;;;
-;;;    Copyright (c) 1986, 1989-93 Massachusetts Institute of Technology
+;;;    Copyright (c) 1986, 1989-95 Massachusetts Institute of Technology
 ;;;
 ;;;    This material was developed by the Scheme project at the
 ;;;    Massachusetts Institute of Technology, Department of
@@ -807,8 +807,7 @@
 (define (%clear-window-buffer-state! window)
   (%set-window-buffer! window false)
   (%set-window-point! window false)
-  (if (%window-start-line-mark window)
-      (clear-window-start! window))
+  (clear-window-start! window)
   (%clear-window-incremental-redisplay-state! window))
 
 (define (%clear-window-incremental-redisplay-state! window)
@@ -837,7 +836,7 @@
        (mark-temporary! (%window-end-clip-mark window))
        (%set-window-end-clip-mark! window false)))
   (%set-window-point-moved?! window false))
-
+\f
 (define-integrable (update-modified-tick! window)
   (%set-window-modified-tick! window
                              (group-modified-tick (%window-group window))))
@@ -849,6 +848,7 @@
             (if (not (eqv? new-value old-value))
                 (begin
                   (%set-window-force-redraw?! window #t)
+                  (clear-window-start! window)
                   (write window new-value))))))
        (buffer (%window-buffer window)))
     (maybe-recache
@@ -1044,11 +1044,15 @@ This number is a percentage, where 0 is the window's top and 100 the bottom."
       (%set-window-point-moved?! window true))
   (window-needs-redisplay! window))
 
-(define-integrable (clear-window-start! window)
-  (mark-temporary! (%window-start-line-mark window))
-  (%set-window-start-line-mark! window false)
-  (mark-temporary! (%window-start-mark window))
-  (%set-window-start-mark! window false)
+(define (clear-window-start! window)
+  (if (%window-start-line-mark window)
+      (begin
+       (mark-temporary! (%window-start-line-mark window))
+       (%set-window-start-line-mark! window #f)))
+  (if (%window-start-mark window)
+      (begin
+       (mark-temporary! (%window-start-mark window))
+       (%set-window-start-mark! window #f)))
   (%set-window-start-line-y! window 0)
   (%set-window-start-column! window 0)
   (%set-window-start-partial! window 0))