patch 7.4.1611
Problem:    The versplit feature makes the code uneccessary complicated.
Solution:   Remove FEAT_VERTSPLIT, always support vertical splits when
            FEAT_WINDOWS is defined.
diff --git a/src/gui.h b/src/gui.h
index f119de5..4e557ad 100644
--- a/src/gui.h
+++ b/src/gui.h
@@ -179,7 +179,7 @@
     /* Values measured in characters: */
     int		top;		/* Top of scroll bar (chars from row 0) */
     int		height;		/* Current height of scroll bar in rows */
-#ifdef FEAT_VERTSPLIT
+#ifdef FEAT_WINDOWS
     int		width;		/* Current width of scroll bar in cols */
 #endif
     int		status_height;	/* Height of status line */