Silverlight: Threads / Delayed Actions / Asynchronous invocations/events - silverlight

Question

I've got the following scenario: when a user moves the mouse out of a popup, I want an animation to happen, and five seconds later, I want to remove a PopUp.
This is the code I expected to do this with is:
private bool leftPopup = false;
public void AnimatePopupOut(object sender, MouseEventArgs e)
{
myAnim.Begin();
(new Thread(new ThreadStart(delayedRemovePopup))).Start();
}
private void delayedRemovePopup()
{
leftPopup = true;
Thread.Sleep(5000);
PopUp.IsOpen = false;
}
The first line, "leftPopup = true" is fine, but the third, "PopUp.IsOpen = false" gives me an access violation exception, probably because this object belongs to the GUI thread. Is there any way I can gain access to the PopUp.IsOpen property? If not, is there another way that I can call an event after some time to do this?
Cheers
Nik

Answer 1

Try using the PopUp.Dispatcher.Invoke(). That will marshal your call back to the UI thread.

Answer 2

Here is a trick I did in WPF. It is ported for use in Silverlight and hangs off of the Dispacher class. I don't know about Maurice's answer because I don't see a "Invoke" method in SL5. I do see the BeginInvoke, which is about usless when it comes to delayed actions.
Usage: You must include the System.Windows namespace in your code file or this extension method won't appear.
// lets say you want to enable a control 1 second after a save event
// lets say you just want to prevent click happy users from going crazy
// This code assumes you disabled the button on the click event
Button b = this.idButton1;
b.Dispatcher.DelayInvoke(TimeSpan.FromSeconds(1), () => { b.Enabled = true; });
That is it. Just one line of code does the trick. Below is the extension class that makes the above code possible.
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Threading;
namespace System.Windows {
public static class DispatcherExtensions {
public static void DelayInvoke<TArg1, TArg2, TArg3>(this Dispatcher dispatcher, TimeSpan delay, Action<TArg1, TArg2, TArg3> action, TArg1 arg1, TArg2 arg2, TArg3 arg3) {
dispatcher.DelayInvoke(delay, (Delegate)action, arg1, arg2, arg3);
}
public static void DelayInvoke<TArg1, TArg2>(this Dispatcher dispatcher, TimeSpan delay, Action<TArg1, TArg2> action, TArg1 arg1, TArg2 arg2) {
dispatcher.DelayInvoke(delay, (Delegate)action, arg1, arg2);
}
public static void DelayInvoke<TArg1>(this Dispatcher dispatcher, TimeSpan delay, Action<TArg1> action, TArg1 arg1) {
dispatcher.DelayInvoke(delay, (Delegate)action, arg1);
}
public static void DelayInvoke(this Dispatcher dispatcher, TimeSpan delay, Action action) {
dispatcher.DelayInvoke(delay, (Delegate)action);
}
public static void DelayInvoke(this Dispatcher dispatcher, TimeSpan delay, Delegate del, params object[] args) {
if (dispatcher == null)
throw new NullReferenceException();
if (delay < TimeSpan.Zero)
throw new ArgumentOutOfRangeException("delay");
if (del == null)
throw new ArgumentNullException("del");
var task = new Task(() => { Thread.Sleep(delay); });
task.ContinueWith((t) => { dispatcher.BeginInvoke(del, args); });
task.Start();
}
}
}