Dispatcher throws InvalidOperationException on Messagebox.Show in Textchanged event

Question

First of all this is the errorlog entry on my error

crash program @ 15-9-2011 15:01:30error:System.InvalidOperationException: Dispatcher processing has been su

Answer 1

See this thread it describes the same problem as yours:

The exception is done on purpose to prevent reentrancy bugs caused by weirdness resulting from altering the visual tree, while such an event (which itself has been triggered by the visual tree altering) is firing. If you really must confirm something when the state of a UI element changes, delaying with Dispatcher.BeginInvoke is probably the right thing to do.

To run code on the UI Thread do the following:

 Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Normal, (Action)(() =>
     {

        if (MessageBox.Show("Geen resultaat gevonden, " + errortext + ".\n Wilt u overschakelen naar handmatig? ", "Handmatig?", MessageBoxButton.YesNo) == MessageBoxResult.Yes)
        {
            RB_handmatig.IsChecked = true;
        }
        else
        {
            //
        }
    }));