How to offer application settings to an end user of your library, at design time, in .net, winforms

I have a library with with a set of classes with a common property that i'd like an end user to be able to override without overriding all the classes.

The important thing is, the property has to be overriden at design time. Lets say, for simplicity's sake, that it's the background c开发者_开发问答olour of a UITypeEditor.

I can do this by putting the setting into the application settings dialog in the ide. However, I can't see how an end user can get access to my settings which are wrapped up in a dll. I've tried importing the dll to another app and adding a setting with the same name to the application settings, but it doesn't override the setting in the dll - which I guess is expected behaviour.

Do I have to put the setting in an external file that the user can edit with notepad?

Seems related to this question, basically it seems you can only have one config file if you want to use the default mechanism, otherwise you have to implement your own.