Cross-thread operation not valid: Control 'richTextBox1' accessed from a thread other than the thread it was created on.

Question

How to do you handle a unsafe crossthread call to add text to the richtextbox in a asynccallback that is on a different thread than the thread that created the richtextbox?

Alan · Answer

Try doing it something like this (.NET 2.0 or later): this.BeginInvoke(new MethodInvoker(delegate() { this.richTextBox1.Text += whatever; }));