Please refer to the attached project for demonstration. To reproduce the crash:
1. Add a PageView control with two pages
2. Place the RadTextBox control in the second page (but launch the program in the first one)
3. Set the RadTextBox.ShowClearButton to True
4. Programmically set RadTextBox.Text = Nothing when the TextBox is not in the current page (won't crash if .Text="" or something else)
5. Switch to the page containing the TextBox -> crash.