F # Winforms Dispatcher BeginInvoke Runtime Delegation Error

Question

I tried to create an F # implementation of some C # code that uses Dispatcher.BeginInvoke to control the user interface from another thread. However, I am struggling to get the code to work.

I tried several different implementations, but I always get "Additional information: Invalid definition for executable delegation method". exception when calling the ToggleVisibility function.

Any input would be greatly appreciated. Here is the code: -

open System
open System.Drawing
open System.Windows.Forms

type ToggleVisibiltyDelegate() = delegate of unit -> unit

type NotifyWindow() as form =
    inherit Form()
    let label1 = new Label()
    do form.InitializeForm

    member this.ToggleVisibility () =

        if (this.Visible) then
            this.BeginInvoke(new ToggleVisibiltyDelegate(fun () -> this.Hide()))
        else
            this.BeginInvoke(new ToggleVisibiltyDelegate(fun () -> this.Show()))

Answer 1

! , ,

type ToggleVisibiltyDelegate() = delegate of unit -> unit

type ToggleVisibiltyDelegate = delegate of unit -> unit