We will add the TimeSpan type to the list of types that allow the operators that you mentioned.
The fix will be available with the Latest Internal Build that we will release later today.
As for the editors, you can define your custom editor as described here.
Here is the online example regarding custom filter editors.
I suppose that you can create a control that will have some numeric up-downs for the hours, minutes and second, but that is up to you. We don't have a built-in TimeSpan editor.
the Telerik team
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