_dragInitiator should be assigned to event.currentTarget

[GoogleCodeExporter]

Once DnDManager.doDrag is called from an event triggered by a complicated 
component, it would throw up something like:

x.core::UITextField@###### can not be converted to mx.core.UIComponent

that was because event.target is the precise element user drags, and it may 
not be an UIComponent. I think the solution is change line 74 of 
DnDManager.as:

    _dragInitiator = UIComponent(evt.target);

to:

    _dragInitiator = UIComponent(evt.currentTarget);

Original issue reported on code.google.com by bige...@gmail.com on 29 Oct 2009 at 8:59