Override InputBindings for ListBox

Question

In my MainWindows, I have a ListBox. I defined commands to cal when user press up/down/del in my Window.InputBindings.

How can I write my ListBox to use my commands and no default command ?

<Window ...>
    <Window.InputBindings>
        <KeyBinding Command="{Binding UndoCommand}"
                    Key="Z"
                    Modifiers="Ctrl"/>
        <KeyBinding Command="{Binding PrevItemCommand}"
                    Key="Up"/>
        <KeyBinding Command="{Binding NextItemCommand}"
                    Key="Down"/>
        <KeyBinding Command="{Binding RemoveCommand}"
                    Key="Delete"/>
    </Window.InputBindings>
    <Grid>
        <ListBox Grid.Row="0" 
                 Grid.Column="0"
                 x:Name="listRes"
                 Style="{StaticResource StyleListBox}"
                 ItemsSource="{Binding Results}"
                 SelectedItem="{Binding SelectedItem}"/>
    </Grid>
</Window>

I added breakpoints in my commands, they are not reached when I use up/down after clicking on an item. They are reached if I use up/down after clicking on an other item.

Edit (explain last sentence):

private ICommand _previtemCommand;
public ICommand PrevItemCommand
{
    get
    {
        if (_previtemCommand == null)
            _previtemCommand = new RelayCommand(OnPrevItem);
        return _previtemCommand;
    }
}
private void OnPrevItem()
{
    // Do something
}

private ICommand _nextitemCommand;
public ICommand NextItemCommand
{
    get
    {
        if (_nextitemCommand == null)
            _nextitemCommand = new RelayCommand(OnNextItem);
        return _nextitemCommand;
    }
}
private void OnNextItem()
{
    // Do something
}

A added breakpoints on functions OnNextItem and OnPrevItem.

• After clicking on an item in the ListBox (ListBox got the focus), up/down keys change selected item but the code doesn't break (my functions are not called)
• After clicking on an check in my windows (ListBox lost the focus), up/down keys the code breaks (my functions are called)

Answer 1

Try to move the KeyBindings to the ListBox itself:

<ListBox Grid.Row="0" 
                 Grid.Column="0"
                 x:Name="listRes"
                 Style="{StaticResource StyleListBox}"
                 ItemsSource="{Binding Results}"
                 SelectedItem="{Binding SelectedItem}">
    <ListBox.InputBindings>
        <KeyBinding Command="{Binding UndoCommand}" Key="Z" Modifiers="Ctrl"/>
        <KeyBinding Command="{Binding PrevItemCommand}" Key="Up"/>
        <KeyBinding Command="{Binding NextItemCommand}" Key="Down"/>
        <KeyBinding Command="{Binding RemoveCommand}" Key="Delete"/>
    </ListBox.InputBindings>
</ListBox>