Question

private void manager_OnWebSiteVisited(object source, WebSiteVisitedEventArgs args)
        {
            if (InvokeRequired)
                txtStatus.BeginInvoke(new WebSiteVisitedCallback(WebSiteVisited), new object[] { args });
            else
                txtStatus.Invoke(new WebSiteVisitedCallback(WebSiteVisited), new object[] { args });
        }

InvokeEvent: Invoke or BeginInvoke cannot be called on a control until the window handle has been created.

i can use if (IsHandleCreated) but i do not know what to do if is not created. How to create it?

Answer 1

Just access the Handle property, it will create the handle if it’s not already created. You can also call the CreateHandle method explicitly.

if (!this.IsHandleCreated)
{
    this.CreateHandle();
}

By the way, your usage of InvokeRequired/Invoke/BeginInvoke is wrong: if InvokeRequired is false, you shouldn’t use Invoke at all, you should call the method directly. I think what you want to do is this:

        if (InvokeRequired)
            txtStatus.Invoke(new WebSiteVisitedCallback(WebSiteVisited), new object[] { args });
        else
            WebSiteVisited(args);