I would expect these keys to go to the beginning and to the end of the list respectively. In the following example, the End key change the tab item.
<Grid>
<StackPanel>
<TabControl Width="200" Height="250">
<TabItem Header="Scroll">
<ListBox Margin="20" x:Name="list" ScrollViewer.PanningMode="VerticalOnly" ScrollViewer.PanningDeceleration="0.00001">
<ListBoxItem Content="Item01"/>
<ListBoxItem Content="Item02"/>
<ListBoxItem Content="Item03"/>
<ListBoxItem Content="Item04"/>
<ListBoxItem Content="Item05"/>
<ListBoxItem Content="Item06"/>
<ListBoxItem Content="Item07"/>
<ListBoxItem Content="Item08"/>
<ListBoxItem Content="Item09"/>
<ListBoxItem Content="Item10"/>
<ListBoxItem Content="Item11"/>
<ListBoxItem Content="Item12"/>
<ListBoxItem Content="Item13"/>
<ListBoxItem Content="Item14"/>
<ListBoxItem Content="Item15"/>
<ListBoxItem Content="Item16"/>
<ListBoxItem Content="Item17"/>
<ListBoxItem Content="Item18"/>
<ListBoxItem Content="Item19"/>
<ListBoxItem Content="Item20"/>
<ListBoxItem Content="Item21"/>
<ListBoxItem Content="Item22"/>
<ListBoxItem Content="Item23"/>
<ListBoxItem Content="Item24"/>
<ListBoxItem Content="Item25"/>
<ListBoxItem Content="Item26"/>
<ListBoxItem Content="Item27"/>
<ListBoxItem Content="Item28"/>
<ListBoxItem Content="Item29"/>
<ListBoxItem Content="Item30"/>
<ListBoxItem Content="Item31"/>
</ListBox>
</TabItem>
<TabItem Header="Tab 2">
<ListBox Margin="20" x:Name="list2" ScrollViewer.PanningMode="Both">
<Button Width="100" Height="150" Click="Button_Click" TouchDown="Button_TouchDown">OK 0</Button>
<Button Width="100" Height="150" >OK 1</Button>
<Button Width="100" Height="150" >OK 2</Button>
<Button Width="100" Height="150" >OK 3</Button>
<Button Width="100" Height="150" >OK 4</Button>
<Button Width="100" Height="150" >OK 5</Button>
<Button Width="100" Height="150" >OK 6</Button>
</ListBox>
</TabItem>
</TabControl>
<Button Margin="20" Width="50" Click="Clicked" TouchDown="Touched">ACTION</Button>
</StackPanel>
</Grid>
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