Within the Visual Studio Designer, under the properties window you are able to select the ForeColor, BackColor etc using color picker. When you wan
I know it's been quite some time...
You can use MergedDictionaries and reference a Resource Dictionary in your App.xml file.
That will put the colors you define in the palette but you would have to include the same Resource Dictionary and reference it in every App.xaml for every application you use, which, in my opinion, is good because sometimes you have to use custom colors for different applications.Custom Color Palette
Something like that