Display all values in a facet block even when a value is selected

Question

I have facet block which looks like:

Categories:
[ ] Category 1
[ ] Category 2
[ ] Category 3
[ ] Category 4

Categories are represented with the ss_category field (single string field). When a category is selected, all the other categories disappear, which makes the block looks like:

Categories:
[X] Category 3

I need all the other categories to remain displayed even when there is an active category, so that the user doesn't have to unclick the active category first then click another one. In other words the block should look like:

Categories:
[ ] Category 1
[ ] Category 2
[X] Category 3
[ ] Category 4

How can I achieve this behavior in Drupal 6?

Answer 1

I need the same behavior, with drupal 7.

I know 2 ways :

Use a facet block use minimal facet count rewrite yourself the missing facets