Previously events used to use class name as a prefix and ignored eo_prefix
when specified. This is no longer the case. Events follow eo_prefix by default
now. In order to get around this for classes where this is undesirable, a new
field event_prefix was added which takes priority over eo_prefix. If neither
is specified, class name is used like previously.
@feature
This removes the conflicts between the different parents and also
indicates that this is to be used internally by widgets and should
not be confused with the normal user visible parent.
It is an internal attribute that should not be used by people
not implementing widgets. Marking it as protected signifies it
as such.
Daniel Kolesa
Tom Hacohen
Cedric BAIL