ComboBoxItem keyboard arrow & Enter press not working - wpf

Question

I have a 'mvvm' based wpf application with a combobox style control Template like so,
<Style x:Key="Itmstyle" TargetType="ComboBoxItem">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ComboBoxItem">
<Button Content="{Binding Txt}" Command="{Binding DataContext.ClickCmd, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type ComboBox}}}"
Background="Transparent" BorderBrush="Transparent">
<Button.InputBindings>
<KeyBinding Key="Enter" Command="{Binding DataContext.ClickCmd, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type ComboBox}}}"/>
</Button.InputBindings>
</Button>
</ControlTemplate>
</Setter.Value>
</Setter>
Style is used like this,
<ComboBox ItemContainerStyle="{StaticResource Itmstyle}"
ItemsSource="{Binding Values}"
DisplayMemberPath="Name"
SelectedIndex="{Binding Indx}"
IsSynchronizedWithCurrentItem="True"/>
When i use the keyboard arrow the buttons (in the style) do not get highlighted, only the dotted focus around the item appears; and when i press Enter key the ClickCmd is not executing.. Any idea! please let me know. Thanks a lot.

Answer 1

If you want a combo selection to both change selection AND fire a command, I'd say the easiest way would be to add a Button as you have done, but process the Click event in code behind to set the combo:
eg
<ComboBox.ItemTemplate>
<DataTemplate>
<Button Content="{Binding Txt}"
Background="Transparent" BorderBrush="Transparent"
Command="{Binding DataContext.ClickCmd, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type ComboBox}}}"
Click="ComboItem_Click"/>
</Button>
</DataTemplate>
</ComboBox.ItemTemplate>
Then in code behind:
private void ComboItem_Click(object sender, RoutedEventArgs e)
{
_combo.SelectedItem = ((Button)e.Source).DataContext;
}