You can use the GenericPageSelector for achieving your goal.
Here is a sample code demonstrating how to include the control in your widget. You have to place it in the .ascx ( the template) file.
<%@ Register Assembly="Telerik.Sitefinity" Namespace="Telerik.Sitefinity.Web.UI" TagPrefix="sf"%>
It will show a treeview with your pages and dropdowns for selecting sites and languages. You can extend this control to match your needs.
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 Sitefinity CMS Ideas&Feedback Portal
and vote to affect the priority of the items