Document methods indicating what kind of client data is associated with an item container (HasClientData() etc.)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64992 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/ctrlsub.h

@@ -347,6 +347,26 @@ public:
     */
     void Delete(unsigned int n);
 
+
+    /**
+       Returns true, if either untyped data (@c void*) or object data (wxClientData*)
+       is associated with the items of the control.
+    */
+    bool HasClientData() const;
+    
+    /**
+       Returns true, if object data (wxClientData*)
+       is associated with the items of the control.
+    */
+    bool HasClientObjectData() const;
+
+    /**
+       Returns true, if untyped data (@c void*) 
+       is associated with the items of the control.
+    */
+    bool HasClientUntypedData() const;
+
+
     //@{
 
     /**