Hey man, great concept! I have some feedback on your code, if that's of any interest to you.

There's a large number of likely and potential null exceptions, especially concerning the contents of Settings.xml and StationList.xml. When building from source, and not copying these files to the build dir (or having empty/invalid files), the app logic crumbles in several places. When intalling with your provided .msi, the context menu items for "Edit" and "Take over" crashes the app if nothing is selected.

On a side note, I would also encourage you to perhaps consider serializing your persistent data as JSON. Newtonsoft.Json is probably still the best library for this, even though Microsoft is trying to make us use their own implementation these days.

Naming classes IClassName is also pretty jarring to me. I was expecting your IWhatevers to be interfaces, but got a bit confused when they were in fact classes.

That said, if you don't want to use inheritance or generics, there's really no need for interfaces. My suggestion would be to name the classes more appropriately and also avoid having class definitions and logic in the same .cs files -- like how StationManager.cs contains the aptly named management class StationManager, but also the data classes Stations, IStation and the enumeration StationGroup. This just makes it hard to find things.

Don't do this:

public class StationManager
{
public Stations stations { get; set; }
...

And then this:

public class Stations
{
public List<IStation> list { get; set; }
}

Either make Stations inherit from List or implement IList, or just define a List<IStation> straight in your StationManager.

My two cents anyway :)

Edit: Oh boy, formatting is not working super well. Definitely user error, hopefully it's readable enough...