(svn r18593) -Fix: GetWidget call case similar to r18591

src/widget.cpp

@@ -2090,7 +2090,11 @@ Scrollbar *NWidgetLeaf::FindScrollbar(Window *w, bool allow_next) const
 	if (this->type == WWT_SCROLL2BAR) return &w->vscroll2;
 
 	if (this->index >= 0 && allow_next && (uint)(this->index) + 1 < w->nested_array_size) {
-		const NWidgetCore *next_wid = w->GetWidget<NWidgetCore>(this->index + 1);
+		/* GetWidget ensures that the widget is of the given type.
+		 * As we might have cases where the next widget in the array
+		 * is a non-Core widget (e.g. NWID_SELECTION) we first get
+		 * the base class and then dynamic_cast that. */
+		const NWidgetCore *next_wid = dynamic_cast<NWidgetCore*>(w->GetWidget<NWidgetBase>(this->index + 1));
 		if (next_wid != NULL) return next_wid->FindScrollbar(w, false);
 	}
 	return NULL;