add EditBoxValue::clone

Change-Id: I03e74d766b85ddd61baa1dbf0f28a663931e7ec6

include/vcl/salnativewidgets.hxx

@@ -487,6 +487,7 @@ public:
         : ImplControlValue(CTRL_EDITBOX, BUTTONVALUE_DONTKNOW, nTextHeight)
     {
     }
+    virtual EditBoxValue* clone() const SAL_OVERRIDE;
 };
 
 #endif

vcl/source/outdev/nativecontrols.cxx

@@ -150,6 +150,12 @@ PushButtonValue* PushButtonValue::clone() const
     return new PushButtonValue( *this );
 }
 
+EditBoxValue* EditBoxValue::clone() const
+{
+    assert( typeid( const EditBoxValue ) == typeid( *this ));
+    return new EditBoxValue( *this );
+}
+
 // These functions are mainly passthrough functions that allow access to
 // the SalFrame behind a Window object for native widget rendering purposes.