Accessing the UI Thread in the right context in tasks

FormWithTasks.fsx

open System.Windows.Forms
open System.Threading.Tasks

let createForm() = 
    let form = new Form()

    let button = new Button()
    button.Text <- "Start"
    form.Controls.Add(button)

    form

let createLabel() =
    let label = new Label()
    label.Location <- new System.Drawing.Point(55, 109); // aka anywhere out of the way

    label.Text <- "Ready?"
    label.Name <- "Status"

    label

let form = createForm()
let label = createLabel()

form.Controls.Add(label)
    
let sleepTask() = 
    System.Threading.Thread.Sleep(5000)

let updateFormTask(previousTask) = 
    
    // this is now in the right context
    label.Text <- "done"
    ()

let task1 = Task.Factory.StartNew(sleepTask)
let task2 = task1.ContinueWith(updateFormTask, TaskScheduler.FromCurrentSynchronizationContext())

form.Show()