There is a XamCombo Editor.In this there are four drop downs.If I am selecting a value in the first drop down then that value should get disabled in the list for the second drop down and if I am selecting a value in the second drop down then the value selected in the first drop down and the value selected in the second drop down should get disabled for the third drop down and so on.

When I am selecting the value thorough the mouse it is working as expected but in case of keyboard I am facing an issue. 

When I am selecting values through the mouse,the values are getting disabled in the drop down and if I am trying to select those values I am unable to do so. But in case of selecting the value through the up and down key of the keyboard the disabled values of the drop down is also getting displayed and are getting selected.I need to avoid the diasbled value selection using the up and down key of the keyboard.

Below is the code snippet:

 <infra:XamDataGrid  

Name="ssnNameDatagrid" <infra:FieldLayout.Fields>                        

<infra:Field                            

Name="SocialSecurityNumber"                            

Width="Auto"                            

Label="{Localize socialSecurityNumber}">                            

<infra:Field.Settings>                                

<infra:FieldSettings                                    

LabelClickAction="Nothing"                                    

EditorType="{x:Type infraEditor:XamComboEditor}">                                    

 <infra:FieldSettings.EditorStyle>                                        

<Style                                            

TargetType="{x:Type infraEditor:XamComboEditor}">                                            

<Setter                                                

Property="ItemsProvider"                                                

Value="{Binding Path=DataContext.ListOfSSNItemsProvider,RelativeSource={RelativeSource Mode=FindAncestor,AncestorLevel=1, AncestorType={x:Type UserControl}} }" />                                            

<Setter                                                

 Property="IsEditable"                                                

 Value="True" />

  <EventSetter                                                

Event="infraEditor:ValueEditor.ValueChanged"                                                

Handler="OnValueChanged" />                                            

<Setter                                                

Property="DropDownButtonDisplayMode"                                                

Value="Always" />