WPF Colors - Accessibility considerations?

Many of the WPF examples and samples that I see seem to have hard-coded colors. These guidelines - http://msdn.microsoft.com/en-us/library/aa350483.aspx suggest not hard coding colors. After building a small application I was disappointed to see that some of my hard-coded color choices made some sections of the application unusable when I changed to a high contrast color scheme.

Assuming that you are working with a 'designed'/visually interesting/stylized UI - how is color accessibility provided? Should the designers provide alternative color schemes for special needs? Should color configuration screens be included in the application? Other solutions?

Any insights and suggestions appreciated.

EDIT: I accepted the answer below because I think the suggestion to have a predefined color scheme based only on system colors is a great idea/solution for my question.

I would be very interested to hear from someone w开发者_StackOverflowho has implemented this scenario for accessibility if there are any technical details/pitfalls/gotchas that would be useful to know when setting this up.

Thanks!

'designed'/visually interesting/stylized UI as you put it often looks really bad if you just swap colors, it also tends to have a lot of colors - so I wouldn't add a color configuration feature to my software.

For accessibility you need either a high-contrast color scheme and the option to change color schemes (not individual colors) - and in that case the designer should provide those colors.

or - even better from an accessibility point of view (but not from a design point of view) - an option to drop all the "visually interesting" styles and drop back to plain windows default black on gray look - using only system colors, without any actual colors defined in the application.

The application will look very ugly in this mode - but customers with vision problems will love you for it.