While it is not possible to accumulate two properties from within the
same block, property accumulation does successfully add to the inherited
values of variables.

I don't know if it should be possible to accumulate properties within
the same property block.  I would imagine so, in which case the behavior
should be considered a bug.

>>
>> … AFAIK the `+' is only supported at this stage for the `var'
>>property: you can't take any property and add a `+' to
>>

FALSE, the "var" property is in no way special when it comes to property
inheritance.  All properties are treated equally.

Best,

-- 
Eric Schulte
http://cs.unm.edu/~eschulte/