The SetText action in Silverlight clears the text prior to simulating the KeyPress actions if the SimulateRealUser is turned on. The request is to include a property which controls that clear text behavior (for a codeless solution). The work-around today is to use a code similar to this: // Type 'aa' into TextInputTextbox, don't clear text (clearCutText = 'false') - the last argument TextBox textBox = Pages.TelerikToolBarFor.SilverlightApp.TextInputTextbox; ArtOfTest.WebAii.Controls.Xaml.XamlControlHelper.SetText(textBox, true, "myText", 10, 100, true, false);