Reworked the HandleDNDposition() method
Reworked the HandleDNDposition() method

* Events are now only fired when the drop is truly accepted, not just
  because it has AcceptDrops and OnEnterDrag event handlers. Event handler
  needs to explicitly set Accept = True.
* Default mime type used is 'text/plain'
* Default drop action is daCopy (or XdndActionCopy)

wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI