System.Object
   C1.Xamarin.Forms.Input.ComboBoxItemLoadingEventArgs
   System.EventArgs
      C1.Xamarin.Forms.Core.AsyncEventArgs
         C1.Xamarin.Forms.Input.AutoCompleteFilteringEventArgs
         C1.Xamarin.Forms.Input.TextBoxAutoCompleteEventArgs
      C1.Xamarin.Forms.Input.CompletedEventArgs
      C1.Xamarin.Forms.Input.DropDownOpenChangedEventArgs
      C1.Xamarin.Forms.Input.DropDownOpenChangingEventArgs
      C1.Xamarin.Forms.Input.TextChangedEventArgs
   Xamarin.Forms.BindableObject
      Xamarin.Forms.Element
         Xamarin.Forms.NavigableElement
            Xamarin.Forms.VisualElement
               Xamarin.Forms.View
                  Xamarin.Forms.InputView
                     Xamarin.Forms.Entry
                        C1.Xamarin.Forms.Input.C1MaskedEntry
                        C1.Xamarin.Forms.Input.C1TextBox
                  Xamarin.Forms.Layout
                     Xamarin.Forms.Layout<T>
                        C1.Xamarin.Forms.Input.C1DropDown
                           C1.Xamarin.Forms.Input.C1ComboBox
                              C1.Xamarin.Forms.Input.C1AutoComplete

Reference

C1.Xamarin.Forms.Input Assembly