Since the IsReadOnly property is set to True no characters different from the ones in the items of the ComboBox can be written or deleted. The Backspace is not working, because the ComboBox is ReadOnly - this is the behaviour by design when in read-only mode - nothing can be changed since is different from the items of the ComboBox. The standard WPF ComboBox works in exactly the same way, which was our objective when we developed the control.
the Telerik team
Explore the entire Telerik portfolio by downloading the Ultimate Collection trial package. Get it now >>