That is, enable its default behaviour. If you wish to create custom behaviour then you'll need to revert to the event-code that you were looking at previously.
However, if we think about how Windows behaves normally, sometimes when we drag it defaults to Copy rather than Move, and some times Move is disabled and a no-entry sign appears.
I do not know if you can tweak the default behaviour (sounds contradictory..) or whether you do, indeed, need to implement your own event-sequence. I suspect the latter.
This post has been edited by andrewsw: 02 February 2013 - 10:02 AM