PHP API Widget Settings

Does there exists, and can someone point me to example code or documentation of, a method for saving settings for a widget. I’ve been writing a quickie widget that lets people view a very specific piece of tracking information for a site I work on, however a few people want to see it in a few different ways. I would like to enable something as simple as a dropdown menu that lets them set the view they want to see and upon revisiting their dashboard for that setting to be persisted.

I’ve been snooping in my spare time and still haven’t figured out how this data is persisted. To be clear I’m talking about persisting data in the layout field in the user_dashboard table. The VisistsSummary table seems to persist settings in the colums field of their object, but I haven’t figured out how yet.