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.
They are OUT params in real
Side note: the doc for this function miss the x parameter in the generated .eo.h file
...if someone want to look at the doc generation code.
Setting the no-render flag on an elm widget had no effect,
as it was not properly propagated to its children. This should
fix that, but I'm not a fan of the solution.
Fixes T3371