Focusable and Enable evolutions

Actualy all Focusable derived widgets has focusable and enable attribute. But enable has an highest priority on focusable. To be short, a disabled widget is not focusable.

In first reflexion this behavior is the best way to manage those two attributes.

But wouldn't it be better if a disabled widget could be focusable ?

Hmn, I see the change has been introduced already. I can't really see why a disabled widget should receive focus? It means I now have to add extra XML:

<button onaction="doAdd">
   %ADD%
   <_enabled>@{active}</_enabled>
   <_focusable>@{active}</_focusable>
</button>

This is not a huge problem, but why the change?

On an unrelated note, it would be great if it were possible to negate values in XML e.g. @{!active}, otherwise I'm forced to define an additional property in my data provider.