Index: wab/cirrus_vga.h
--- wab/cirrus_vga.h.orig
+++ wab/cirrus_vga.h
@@ -91,6 +91,8 @@ typedef struct DisplaySurface {
     struct PixelFormat pf;
 } DisplaySurface;
 
+struct DisplayState;
+
 typedef struct DisplayChangeListener {
     int idle;
     UINT64 gui_timer_interval;
