c# - Cross-thread operation not valid: Control 'listBox1' accessed from a > thread other than the thread it was created on

While I am trying to add items to a ListBox, I'am getting the following error:

Cross-thread operation not valid: Control 'listBox1' accessed from a
thread other than the thread it was created on.

Here is tried code:

private void Form1_Load(object sender, EventArgs e)
{

    Jid jd = new Jid("USERNAME");
    xmpp.Open(jd.User, "PASSWORD");
    xmpp.OnLogin += new ObjectHandler(xmpp_OnLogin);
    agsXMPP.XmppConnection p;
    xmpp.OnPresence += new PresenceHandler(xmpp_OnPresence);
}
void xmpp_OnPresence(object sender, Presence pres)
{
    listBox1.Items.Add(pres.From .User ); --- **HERE I AM GETTING ERROR.**
}

I am little bit new in C# and also with threading, I googled and checked many articles including SO, But still I don't know how to solve the problem.

Answer

Try this out

void xmpp_OnPresence(object sender, Presence pres)
    {
  this.Invoke(new MethodInvoker(delegate()
                {


listBox1.Items.Add(pres.From .User ); --- **HERE I AM GETTING ERROR.**

   }));
}