diff --git a/src/window.cpp b/src/window.cpp
--- a/src/window.cpp
+++ b/src/window.cpp
@@ -37,6 +37,7 @@ static Window *_mouseover_last_w = NULL;
 Window *_z_windows[MAX_NUMBER_OF_WINDOWS];
 Window **_last_z_window; ///< always points to the next free space in the z-array
 
+byte _no_scroll;
 Point _cursorpos_drag_start;
 
 int _scrollbar_start_pos;