I am able to access styles that appear in the system styles folders, such as ArcGIS 2D. The code looks like this:
var arcgis_2d = ArcGIS.Desktop.Core.Project.Current.GetItems<StyleProjectItem>().First(si => si.Name == "ArcGIS 2D");
But that code does not allow me to get to styles in the Favorites folder:
How would I access styles in the Favorites folder? Thanks.
Accessing the favorite style in a project is not supported. But you should be able to create your own personal style and add items to it. This personal style will be accessible using the SDK.