By default you are able to create a custom sorting for a widget by editing the SortingExpression setting in the Control Defition -> Views section of the control. However there is no such setting, which we will investigate. In the meantime I can suggest you to create a new control in which you can inherit the functionality of the original control and apply some custom sorting of yours.
Here is a quick code snippet which sorts pages instead of lists, which you can use as reference:
.OrderByDescending(pN => pN.LastModified)
the Telerik team
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items