The RadSlider control does not offer such functionality out of the box. As you yourself mentioned, you can use the client events of the control to implement the described behavior.
What you actually need to "fix" is only the information that you display. That is why, I would recommend that you do the following:
- Before you update the input, check the value of the slider and calculate the value you want to display in the input based on the selectionStart/selectionEnd of the slider.
- Update the input with the calculated value and not with the value of the RadSlider.
All the best,
the Telerik team