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copied!<p>I guess your code relates to Windows Forms.<br/> You call <code>BeginInvoke</code> if you need something to be executed asynchronously in the UI thread: change control's properties in most of the cases.<br/> Roughly speaking this is accomplished be passing the delegate to some procedure which is being periodically executed. (message loop processing and the stuff like that)</p> <p>If <code>BeginInvoke</code> is called for <code>Delegate</code> type the delegate is just invoked asynchronously.<br/> (<code>Invoke</code> for the sync version.)</p> <p>If you want more universal code which works perfectly for WPF and WinForms you can consider Task Parallel Library and running the <code>Task</code> with the according <a href="http://msdn.microsoft.com/en-us/library/system.threading.synchronizationcontext.aspx" rel="noreferrer">context</a>. (<code>TaskScheduler.FromCurrentSynchronizationContext()</code>)</p> <p>And to add a little to already said by others: Lambdas can be treated either as anonymous methods or <a href="http://msdn.microsoft.com/ru-ru/library/system.linq.expressions.expression.aspx" rel="noreferrer">expressions</a>.<br/> And that is why you cannot just use <code>var</code> with lambdas: compiler needs a hint.<br/></p> <p><strong>UPDATE:</strong></p> <p>this requires .Net v4.0 and higher</p> <pre><code>// This line must be called in UI thread to get correct scheduler var scheduler = System.Threading.Tasks.TaskScheduler.FromCurrentSynchronizationContext(); // this can be called anywhere var task = new System.Threading.Tasks.Task( () => someformobj.listBox1.SelectedIndex = 0); // also can be called anywhere. Task will be scheduled for execution. // And *IF I'm not mistaken* can be (or even will be executed synchronously) // if this call is made from GUI thread. (to be checked) task.Start(scheduler); </code></pre> <p>If you started the task from other thread and need to wait for its completition <code>task.Wait()</code> will block calling thread till the end of the task.</p> <p>Read more about tasks <a href="http://www.albahari.com/threading/part5.aspx" rel="noreferrer">here</a>. </p>

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