clickable categories

[Robert Collins]

Ok, coding clickable categories is (mostly) easy.

How should they behave?

*  on clicking, all packages rotate 1 option. (ie prev->curr).
or
*  the category has a spin control, and on clicking this, sets all
packages to the closest match possible for the spin control. I.e. if the
category is set to prev, an a package has no prev, the package goes to
"installed version" or "curr".

Rob