Please describe the problem:
When I try to change the Evolution preferences the OK button will ghost and not allow my changes to be saved. Example if I try to set the signature to be inserted in each e-mail I generate automatically, the OK button will ghost. If I try to set the e-mail polling the OK button ghosts.

Steps to reproduce:
1. Click on Edit --> preferences
2. Make change to any preference setting
3. 


Actual results:
The OK button will ghost and changes cannot be saved.

Expected results:
I would expect the OK button to stay functional so I can save my changes.

Does this happen every time?
Yes

Other information: