Thanks for your reply everyone. In case someone else is looking for similar solutions, I'd like to share another idea:
Call .CheckRules when user makes a control with broken rules not visible (e.g. user changes tabs) . If broken rules exist for a specific BO, display an InfoBox notification with broken rules. This way user is informed of broken rules as he clicks through the tabs. I just implemented this, it looks good and it's user friendly.
Thanks.