Index: graphics.c
===================================================================
--- graphics.c	(revision 8406)
+++ graphics.c	(working copy)
@@ -271,8 +271,13 @@
 		graphics_update();
 		
 		// Start scrolling unless we already are
-		// XXX Bug 16838, this should not be called if s->once is set
-		if (!s->os) {
+		//  and only if we have not scrolled once already
+		if ((!s->os) && (s->once != 2)) {
+
+			// Set once to scrolled once already
+			if (s->once == 1)
+				s->once = 2;
+
 			anim_scroll_grf_start(s);
 		}
 		
@@ -335,6 +340,10 @@
 		
 		// Kill any previous scrolling
 		anim_scroll_grf_stop(s);
+
+		// Allow another scroll once
+		if (s->once == 2)
+			s->once = 1;
 		
 		break;