patch 7.4.2279
Problem:    Starting diff mode with the cursor in the last line might end up
            only showing one closed fold. (John Beckett)
Solution:   Scroll the window to show the same relative cursor position.
diff --git a/src/window.c b/src/window.c
index 65d8b36..6943c8f 100644
--- a/src/window.c
+++ b/src/window.c
@@ -5674,8 +5674,6 @@
     void
 win_new_height(win_T *wp, int height)
 {
-    linenr_T	lnum;
-    int		sline, line_size;
     int		prev_height = wp->w_height;
 
     /* Don't want a negative height.  Happens when splitting a tiny window.
@@ -5701,6 +5699,16 @@
     wp->w_height = height;
     wp->w_skipcol = 0;
 
+    scroll_to_fraction(wp, prev_height);
+}
+
+    void
+scroll_to_fraction(win_T *wp, int prev_height)
+{
+    linenr_T	lnum;
+    int		sline, line_size;
+    int		height = wp->w_height;
+
     /* Don't change w_topline when height is zero.  Don't set w_topline when
      * 'scrollbind' is set and this isn't the current window. */
     if (height > 0