1 files changed, 9 insertions, 1 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index ba33e111387..562e10aafbd 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -1060,6 +1060,11 @@ done:
       int start, end, whole;
 
       /* Calculate the start and end positions for the current window.
+         At some point, it would be nice to choose between scrollbars
+         which reflect the whole buffer size, with special markers
+         indicating narrowing, and scrollbars which reflect only the
+         visible region.
+
          Note that minibuffers sometimes aren't displaying any text.  */
       if (! MINI_WINDOW_P (w)
           || (w == XWINDOW (minibuf_window) && ! echo_area_glyphs))
@@ -1068,7 +1073,10 @@ done:
           /* I don't think this is guaranteed to be right.  For the
              moment, we'll pretend it is.  */
           end = Z - XINT (w->window_end_pos);
-          whole = Z - BEG;
+          whole = ZV - BEGV;
+
+          if (end < start) end = start;
+          if (whole > (end - start)) whole = end - start;
         }
       else
         start = end = whole = 0;