In the Dot Net Nuke module that I'm developing I need to separate the controls into several different areas. Unfortunately, it appears that Dot Net Nuke thinks that any control identified by a control key is an 'edit' screen and changes the skin automatically.
This is a topic that folks have a lot of difficulty understanding and working around. For starters, see my blog post on module isolation.
The short story is that you'll get module isolation (which includes switching to the edit skin) whenever you use a control key in the URL to change controls. If you don't want that behavior, you'll have to work around it.
There are a number of established techniques, from simple do-it-yourself to more complex arrangements. In my blog post, I point you to Michael Washington's navigation tutorial, which includes using a PlaceHolder and loading controls dynamically into that, using a MultiView control, or using multiple module definitions (which is a whole other paradigm).