Recently I was approached via PM about dialog system used in our game. I planned to write a tutorial, but it turned out to be to problematic — my ability to explain things is severely limited. So, instead, I'm sharing a sample scene — the system is so easy that you shouldn't have any problems getting a grasp of it.
Here's how it looked in action:
For our game we incorporated a classical Visual Novel style dialogues, with character animations, dialog portraits and do on. We decided against use of default VS dialog system (can't really remember why) and opted to create our own solution with action parts only. The system is very flexible, can be easily modified (selecting an answer rises relationship value and so on) BUT it's definitely more time-consuming to use than default VS dialog system, and since it relies only on action parts, there is zero automation — you will have to manually trace dialog levels, toggle conditions, switch character portraits and so on. You've been warned. Anyway, maybe someone find it useful.