EZ_DnDGetMatchedConversionTargets returns the list of targets the
both the drag-source and the drop-site convert. The list of matched
targets is available only after a drag is droped at a valid drop site.
If DnD is not currently active, the returned values are random.
This procedure is intended for to be used by
Drag-Start-Filters and Drop-Start-Filters to select best conversion