Represents a custom document used by a {@linkcode CustomEditorProvider}.
Custom documents are only used within a given CustomEditorProvider. The lifecycle of a CustomDocument is
managed by the editor. When no more references remain to a CustomDocument, it is disposed of.
Fields
dispose():Void
Dispose of the custom document.
This is invoked by the editor when there are no more references to a given CustomDocument (for example when
all editors associated with the document have been closed.)