Cannot type `Key.Space` into a `TextBox` inside a `SelectingItemsControl`

Describe the bug SelectingItemsControl.OnKeyDown handles certain KeyEventArgs events.

The event being marked as handled causes Avalonia.Win32.WindowImpl.AppWndProc to set its _ignoreWmChar field and not to raise an event when the WM_CHAR message is subsequently received, which finally causes Avalonia.Input.KeyboardDevice.ProcessRawEvent not to create a TextInputEventArgs event.

The space key is thus never seen by TextBox, even though it has keyboard focus when the key is pressed.

To Reproduce Create a window with this XAML:

<ListBox>
    <TextBox/>
</ListBox>

Try typing into the text box. You will not be able to type a space character.

Expected behavior Normal text input.

Desktop (please complete the following information):

• OS: Windows 10
• Version 11preview4

[timunie]

@workgroupengineering you are good to go. The PR will be accepted 👍

Thanks for looking into it.

🙏 Please add a unit test for this as we really need to make sure this will not happen again.

[workgroupengineering]

Hi, I have a similar problem with the following xaml:

    <ListBox ItemsSource="{Binding Models}"
            Grid.IsSharedSizeScope="True">
      <ListBox.DataTemplates>
        <DataTemplate DataType="l:Model">
          <Grid>
            <Grid.ColumnDefinitions>
              <ColumnDefinition Width="Auto" SharedSizeGroup="a"/>
              <ColumnDefinition Width="*"/>
            </Grid.ColumnDefinitions>
            <TextBlock Text="{Binding Id}"/>
            <TextBox Text="{Binding Description}"/>
          </Grid>
        </DataTemplate>
      </ListBox.DataTemplates>
    </ListBox>  

Regression is introduced with pr #11455 when keyboard interaction is moved from SelectingItemsControl to ListBox the fix for pr #9629 has been lost.

Can I redo the fix of pr #9629 on the ListBox?