Add gfx_debug console command

src/gfx_func.h

@@ -156,6 +156,12 @@ static inline int CenterBounds(int min, int max, int size)
 }
 
 /* window.cpp */
+enum DrawOverlappedWindowFlags {
+	DOWF_NONE         =      0,
+	DOWF_MARK_DIRTY   = 1 << 0,
+	DOWF_SHOW_DEBUG   = 1 << 1,
+};
+DECLARE_ENUM_AS_BIT_SET(DrawOverlappedWindowFlags)
 void DrawOverlappedWindowForAll(int left, int top, int right, int bottom);
 
 void SetMouseCursorBusy(bool busy);