[Design] Determining that collections behave like categories

[Philippe Bossut]

Grant Baillie wrote:

> A "+" button next to the "Appears In..." item in the detail view as a  
> clue?

Or making the whole "Appears In..." field editable.

Anyway, I remember that we played with a similar idea in Entourage and 
implemented "search folders" so that, indeed, emails appeared in 
different places (instead of being filtered and moved). This feature 
tested terribly. It's somewhat disorienting for people to have one thing 
appearing in 2 places at the same time...

Cheers,
- Philippe

PS: on the subject of locations (places) and items, it seems that some 
of it is so hard wired in our brains that using it is the best memory 
strategy known. See:
    http://news.bbc.co.uk/2/hi/health/3152502.stm
    http://www.newscientist.com/article.ns?id=dn3181