Thank you for writing.
By design, the ValueChanged
event is fired when handling mouse move of the thumb element with left mouse button down. The value is updated as soon as you move the thumb to the new position, not when you release the mouse. This default behavior can't be changed. If we have similar requests from other customers we will consider it in the future control's improvement.
I hope this information helps. Should you have further questions I would be glad to help.
Telerik by Progress