[Development] Why don't we have notify signal for all of the properties?

[Tr3wory]

Hi all!

I found the QML's property binding system really powerful, but as far
as I understand on the C++ side it relies on the property's NOTIFY
signal.
I know the notify signal is added around Qt 4.6, and as far as I
understand we couldn't add more signals to existing properties in the
4.x timeframe because of the binary compatibility. (Please correct me
if I'm wrong about this.)

If I'm right about this it means we can't add these after 5.0... So do
we have any plans to add more signal in 5.0?
I think these can make easier to use existing Qt classes from QML, and
I think these can be useful even in the good old C++.
(And also make it possible to create a BindingElement like class in
C++ (this is what I'm experimenting with right now)).

What do you think?

Cheers,

tr3w