Union with a TypeConverter for use as a literal in WPF

Tabs.fsi

open System.ComponentModel

[<TypeConverter(typedefof<TabsConverter>)>]
type Tabs =
    | Item
    | Hour
    | Event
    | Search

and TabsConverter() =
    inherit TypeConverter()

    override __.CanConvertFrom (context, sourceType) =
        if sourceType = typedefof<string> then true
        else base.CanConvertFrom (context, sourceType)

    override __.ConvertFrom (context, culture, value) =
        match value with
        | :? string as x ->
            match x with
            | "Item" -> Item :> obj
            | "Hour" -> Hour :> obj
            | "Event" -> Event :> obj
            | "Search" -> Search :> obj
            | _ -> base.ConvertFrom (context, culture, value)
        | _ -> base.ConvertFrom (context, culture, value)

    override __.ConvertTo (context, culture, value, destinationType) =
        if destinationType <> typedefof<string> then base.ConvertTo (context, culture, value, destinationType)
        else
            match value with
            | :? Tabs as x -> (sprintf "%A" x) :> obj
            | _ -> base.ConvertTo (context, culture, value, destinationType)