--- GLwDrawA.h.bak	2014-10-13 13:00:18.140625400 +0100
+++ GLwDrawA.h	2014-10-13 13:01:06.581762300 +0100
@@ -136,7 +136,7 @@
 typedef struct _GLwMDrawingAreaClassRec	*GLwMDrawingAreaWidgetClass;
 typedef struct _GLwMDrawingAreaRec	*GLwMDrawingAreaWidget;
 
-GLAPI WidgetClass glwMDrawingAreaWidgetClass;
+extern GLAPI WidgetClass glwMDrawingAreaWidgetClass;
 
 
 #else
@@ -144,7 +144,7 @@
 typedef struct _GLwDrawingAreaClassRec	*GLwDrawingAreaWidgetClass;
 typedef struct _GLwDrawingAreaRec	*GLwDrawingAreaWidget;
 
-GLAPI WidgetClass glwDrawingAreaWidgetClass;
+extern GLAPI WidgetClass glwDrawingAreaWidgetClass;
 
 
 #endif