D Properties when?

[Hipreme]

This is no news in the programming world, yet, we still don't 
have it.

This is very important for I can define a good API in which I 
could increase my engine performance.
With that, I could implement fields with dirty flags and not make 
the API looks dirty (no pun intended).


Think of an object with X and Y position. I want to be able to 
when its value changes, it sets a dirty flag to true. The problem 
is that I'm unable to do `X+= 50` after that. I need to do `X = X 
+ 50`, this is not news but still makes the API inconsistent and 
more verbose.
I don't care how this is implemented, I only want this some day 
to not make it look ugly.