Thank you for contacting us.
The initial requirement that you have could not be achieved due to the way that the RadTimePicker is implemented. The values are actually changed/set when the control is blurred.
Notwithstanding, you could achieve the desired functionality entirely on client. For your convenience I have prepared for you a sample page with the functionality in question. Please refer to the attached files and see if this approach works for your scenario.
Just one clarification. Please note that the RadTimePicker is actually setting a Date object and not just time values. This means that you could not set the difference between two pickers to another picker. As you will see in the provided sample page, the difference is parsed to hours and minutes and is set in text box control.
If further assistance is needed, please do not hesitate to contact us again.
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to the blog feed