In the WPF Demos (RadAutoCompleteBox RadHighlightTextBox), the only code shown is a skeleton XAML and not the parts of the code that actually do the work. Where can I find that example's code? I searched the Telerik GitHub repos to no avail.
We are aware of this behavior and we are working on fixing it.
In the meantime, I have extracted the code from the example into a sample project for you to test. It contains the code for the RadAutoCompleteBox and RadHighlightTextBox controls.
I hope the provided information will be of help to you.