Multiple subtyping with alias this and nested classes

[language_fan]

On Sat, 03 Oct 2009 13:52:51 -0300, Leandro Lucarella wrote:

>> Scala supports that with mixins, D supports that with multiple
>> subtyping.
> 
> I don't know what you mean about multiple subtyping.

I have also not seen the specs for this feature. How does multiple 
subtyping work exactly in D? Does it have exactly the same semantics as 
using interfaces + mixing in the traits? Why was the 'alias foo this' 
chosen if you are also planning to add support for Scala like traits 
(some other thread here recently discussed this). Andrei, you probably 
know how Scala chooses the overrides and overloads when traits have 
conflicts. How does D handle this?