supporting failed data conversions

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@49037 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/mac/carbon/dataobj.cpp

@@ -283,7 +283,8 @@ void wxDataObject::AddToPasteboard( void * pb, int itemID )
         {
             // empty the buffer because in some case GetDataHere does not fill buf
             memset( buf, 0, sz );
-            GetDataHere( array[ i ], buf );
+            if ( GetDataHere( array[ i ], buf ) )
+            {
                 int counter = 1 ;
                 if ( thisFormat.GetType() == wxDF_FILENAME )
                 {
@@ -316,6 +317,7 @@ void wxDataObject::AddToPasteboard( void * pb, int itemID )
                             (CFStringRef) thisFormat.GetFormatId() , data, kPasteboardFlavorNoFlags);
                     CFRelease( data );
                 }
+            }
             free( buf );
         }
     }