This is not a personal post as such, but I have seen all over Facebook recently a post about a father who still goes around to cook breakfast for his ex wife on her birthday because he wants to set a good example for his kids... but there's no mention of any current partners on the scene 
This has caused a lot of debate between my friends and I just wondered what other people's views are on the level of involvement your or DP's ExW/ExH has in their lives?
What do you think is appropriate and where are lines drawn?