I have set up a filter that adds unknown addresses to the address book. The filter "action" add to address book has an option for the folder into which to add. When I open the filter config dialog to change that option, and I change only that and nothing else, then I cannot "Apply" the change because the "Apply" button doesn't see it.
Workaround: Change something else, e.g. in the Filter conditions, and change it back. Then Apply becomes available.
Expected behaviour: Apply should be aware of the setting and allow to save it.

Reproducible: Always

Steps to Reproduce:
1. You need at least two address book folders.
2. Create a filter that adds addresses to address book.
3. Close the filter setting and go back to the filter setting.
4. Change the "Save into folder" dropdown of the addressbook action.

Actual Results:  
"Apply" greyed out.

Expected Results:  
"Apply" becomes available