1 files changed, 16 insertions, 11 deletions

diff --git a/src/viewport.cpp b/src/viewport.cpp
index 303e02760..3e4c2d273 100644
--- a/src/viewport.cpp
+++ b/src/viewport.cpp
@@ -266,35 +266,36 @@ void InitializeWindowViewport(Window *w, int x, int y,
 
 static Point _vp_move_offs;
 
-static void DoSetViewportPosition(const Window *w, int left, int top, int width, int height)
+static void DoSetViewportPosition(Window::IteratorToFront it, int left, int top, int width, int height)
 {
-	for (const Window *w : Window::IterateFromBack(w)) {
+	for (; !it.IsEnd(); ++it) {
+		const Window *w = *it;
 		if (left + width > w->left &&
 				w->left + w->width > left &&
 				top + height > w->top &&
 				w->top + w->height > top) {
 
 			if (left < w->left) {
-				DoSetViewportPosition(w, left, top, w->left - left, height);
-				DoSetViewportPosition(w, left + (w->left - left), top, width - (w->left - left), height);
+				DoSetViewportPosition(it, left, top, w->left - left, height);
+				DoSetViewportPosition(it, left + (w->left - left), top, width - (w->left - left), height);
 				return;
 			}
 
 			if (left + width > w->left + w->width) {
-				DoSetViewportPosition(w, left, top, (w->left + w->width - left), height);
-				DoSetViewportPosition(w, left + (w->left + w->width - left), top, width - (w->left + w->width - left), height);
+				DoSetViewportPosition(it, left, top, (w->left + w->width - left), height);
+				DoSetViewportPosition(it, left + (w->left + w->width - left), top, width - (w->left + w->width - left), height);
 				return;
 			}
 
 			if (top < w->top) {
-				DoSetViewportPosition(w, left, top, width, (w->top - top));
-				DoSetViewportPosition(w, left, top + (w->top - top), width, height - (w->top - top));
+				DoSetViewportPosition(it, left, top, width, (w->top - top));
+				DoSetViewportPosition(it, left, top + (w->top - top), width, height - (w->top - top));
 				return;
 			}
 
 			if (top + height > w->top + w->height) {
-				DoSetViewportPosition(w, left, top, width, (w->top + w->height - top));
-				DoSetViewportPosition(w, left, top + (w->top + w->height - top), width, height - (w->top + w->height - top));
+				DoSetViewportPosition(it, left, top, width, (w->top + w->height - top));
+				DoSetViewportPosition(it, left, top + (w->top + w->height - top), width, height - (w->top + w->height - top));
 				return;
 			}
 
@@ -380,7 +381,11 @@ static void SetViewportPosition(Window *w, int x, int y)
 		i = top + height - _screen.height;
 		if (i >= 0) height -= i;
 
-		if (height > 0) DoSetViewportPosition(w->z_front, left, top, width, height);
+		if (height > 0) {
+			Window::IteratorToFront it(w);
+			++it;
+			DoSetViewportPosition(it, left, top, width, height);
+		}
 	}
 }