Add support for accessing the MapQuestTiles. via their new Static API :

http://www.mapquestapi.com/staticmap/

Since 11 July 2016, MapQuest Tiles cannot be directly accessed.

http://devblog.mapquest.com/2016/06/15/modernization-of-mapquest-results-in-changes-to-open-tile-access/ 


To disable the MapQuest option in RadMap's OpenStreetMapProvider you can use the following code:

<telerik:RadMap x:Name="radMap" >
            <telerik:RadMap.Provider>
                <telerik:OpenStreetMapProvider x:Name="provider" />
            </telerik:RadMap.Provider>                
        </telerik:RadMap>

 InitializeComponent();

      string mapQuestCommandName = "Telerik.Windows.Controls.Map.OpenStreetMapQuestSource";
      CommandDescription command = this.provider.Commands.Where(x => x.CommandParameter.ToString() == mapQuestCommandName).FirstOrDefault();
      this.provider.Commands.Remove(command);

In R3 2016 this option will be disabled by default.