Updates the acceptable drag types of all text views associated with the receiver's layout manager.
If the receiver is editable and is a rich text view, causes all text views associated with the receiver’s layout manager to register their acceptable drag types. If the text view isn’t editable or isn’t rich text, causes those text views to unregister their dragged types.
Subclasses can override this method to change the conditions for registering and unregistering drag types, whether as a group or individually based on the current state of the text view. They should invoke this method when that state changes to perform the necessary update.