Add multiple thumbs (more than 2). This would enable multiple ranges.

Implement out-of-the-box support for ToolTip to display the value during a drag even when the RadSlider.IsDeferredDraggingEnabled property is set to True.

Available in R1 2017 Release

The RadSlider supports the "increase" and "decrease" handles, but "decrease" only decrements SelectionStart, and "increase" only increments SelectionEnd. Ideally there'd be an option for *two* sets of buttons at each end of the slider, an "increase" and "decrease" pair, so that both SelectionStart and SelectionEnd could be *either* increased *or* decreased independently. See the attached illustration. Thanks! 

There is IncreaseDecreaseHandlesOnBothEnds SDK demo available since R3 2016 Release.
https://github.com/telerik/xaml-sdk/tree/master/Slider/IncreaseDecreaseHandlesOnBothEnds

When the slider is hosted in a TabControl its bindings don't work as expected when switching tabs

Fixed in Q3 2014