How can the second exposed filter items be defined by the selection in a first exposed filter ?

Hi,

I would like to have to exposed filters in my view, such that a user select an item in the first exposed filter, which will then determine the content of the second exposed filter.

So there is a certain content type containing these two fields (with multiple items in each), and I would like that when an item of the first field is choosed, then only the items of the second field which will actually lead to a (non-empty) result to appear.

I looked and found some things but they don't allow that (I think):
- http://drupal.org/node/450864 : redirects immediately to hierarchical select, which is for taxonomy hierarchies
- http://drupal.org/node/450872 : redirects immediately to faceted search, which doesn't do that...
- http://drupal.org/node/526956 : is different (but close), because here we don't want in the second exposed filter all the items of a column database, just the ones which will actually lead to a view with results in it.

I think this could be done with the attachement type in views. (?) I found this :
http://www.agileapproach.com/blog-entry/the-views2-attachment-display
... but can't get what I want with it...

Does anyone have some advice on this ?
Thanks a lot for your help !
Xavier