>I was wondering if anyone knew if it was possible to make changes to
an application's App.config file at runtime and then be able to access
those changes immediately.
Not without a lot of code of your own, for two main reasons:
1) The .NET configuration system will read its settings at app startup
only, and not ever after that - so any changes you may have made will
never be reflected in the ConfigurationSettings object
2) The .NET config system does not offer any way to manipulate an
existing .config file out of the box. And this is by design - under
normal circumstances, your app's .config file will reside in the app's
directory, where regular users should *not* have any write permissions
in the first place - so you wouldn't be able to modify that file
anyway.
Instead, for user settings, I'd recommend using some kind of a
XML-based config file, and store it e.g. using the IsolatedStorage
classes, to ensure the user can actually write back changes to his
settings!
Also, there are a ton of free third-party configuration classes and
components - just go search
www.codeproject.com for "configuration
..NET" or something like that - you'll find quite a few links.
Marc