canvas::Layout: support for contents margins.

[simgear.git] / simgear / props / PropertyBasedElement.hxx

diff --git a/simgear/props/PropertyBasedElement.hxx b/simgear/props/PropertyBasedElement.hxx
index 52af9b30bb79fcd3cc033edf3823be011d1af6fe..27eff170ce731a32d49f31d4272662ddedd8563a 100644 (file)
--- a/simgear/props/PropertyBasedElement.hxx
+++ b/simgear/props/PropertyBasedElement.hxx
@@ -30,7 +30,7 @@ namespace simgear
    */
   class PropertyBasedElement:
     public SGPropertyChangeListener,
-    public SGWeakReferenced
+    public virtual SGVirtualWeakReferenced
   {
     public:
       PropertyBasedElement(SGPropertyNode* node);