Having just published Simple.Wpf.Terminal as a nuget package I wanted the ability to skin the user control - the more flexibility in the way it looks the more likely it will be used by other devs :) Before getting into the detail, lets look at the solution working in the test harness for my WPF F# REPL Engine , shown below are four different themes applied dynamically at run-time - no recompilation required to change the theme: Previously in larger WPF apps I've relied upon third-party control vendors like Telerik to provide theming support. Typically they provide good solutions to the problem with multiple themes supported as standard, and when you're already using their third party controls the use of their themes makes sense. But when you're developing a small UI component you don't want to add (& support) such a large footprint just to add themes to your niche control. A theme is a collection of Styles grouped into a ResourceDictionary in WPF. A ...