GtkData -- abstract base class for objects containing data.
The GtkData object is a very simple object intended to be used as a base
class for objects which contain data (i.e. the 'Model' in the object-oriented
Currently it is not very useful since all it provides is a "disconnect" signal.
This signal could be emitted by a GtkData subclass to notify any 'Views'
that they should disconnect from the GtkData (the 'Model'), possibly just
before the GtkData is destroyed.
The GtkData struct contains no public fields.
The "disconnect" signal
Emitted to notify any views on the GtkData object to disconnect from it,
possibly because the GtkData object is about to be destroyed.
|data :||the object which received the signal.
|user_data :||user data set when the signal handler was connected.|