It's not beta. It's about to die.
Also, move #define ELM_WIDGET_BETA to the common header file, as it is
consequently required by ALL widgets. :(
Ping @bu5hm4n :)
Ref T5363
Lacking a proper internal tag, I'm using both protected (it is
in fact a protected access function) and beta (to mark as unstable,
not real API).
New smart objects based on EO only should rely on constructor,
finalize and destructor exclusively. In theory, this should be fine.
Unfortunately it may be impossible to inherit from the Efl.Ui.Win
class as it uses a really bad hack and calls super.constructor
inside the finalize method.