Provide information about the clicked control in the arguments of RadContextMenu DropDownOpening/ed event. This will help easily determine which control is clicked in case the same RadContextMenu is associated with more than one control.
Adding my vote for this Issue ! This functionnality is avaible in the legacy Winforms Context Menu (ContextMenuStrip) as a property named SourceControl and it's a common feature ! http://msdn.microsoft.com/en-us/library/system.windows.forms.contextmenust