Callbacks are implemented as listener interfaces. functions like
- all the underscore characters where dropped ("_") as they look ugly
- when a name is composed by more than one word the first character of each word is capitalized
- all the "g" prefixes where dropped
- all the "gdk", "gtk" tokens where dropped
are not implemented at all as it makes no sense to have a button executing some action, buttons are there to pass on user events not executing actions.
This is specially true since D does not support anonymous inner classes.
With an anonymous inner class that extends the button class we could to execute some action but then we would have the context of the outer class.
(If D ends up supporting anonymous inner classes maybe this could be reviewed)
See the Listening to events page.