Shift+Tab not working in TreeView control

Question

I cannot get backwards navigation using Shift+Tab to work in a TreeView that contains TextBoxs, forward navigation using Tab works fine and jump from TextBox to TextBox insi

Answer 1

You don't have to use a custom class inherited from TreeView:

treeView.PreviewKeyDown += this.HandleTreeView_PreviewKeyDown

together with:

private void HandleTreeView_PreviewKeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyboardDevice.Modifiers.HasFlag(ModifierKeys.Shift)
        && e.Key == Key.Tab)
    {
        var focusedElement = Keyboard.FocusedElement;
        if (focusedElement != null)
        {
            focusedElement.MoveFocus(FocusNavigationDirection.Previous, 1);
        }

        e.Handled = true;
    }
}

Also works fine.

With this solution you could, for example, create a custom behavior and attach it to your TreeView.

Answer 2

If you look in the TreeView.OnKeyDown handler using ILSpy/Reflector, you can see the cause of your issues. The TreeView has special handling when Shift+Tab is pressed. The relevant code is:

Key key = e.Key;
if (key != Key.Tab) {
    // ... 
}
else {
    if (TreeView.IsShiftKeyDown && base.IsKeyboardFocusWithin &&
        this.MoveFocus(new TraversalRequest(FocusNavigationDirection.Previous))) {
        e.Handled = true;
        return;
    }
}

Unfortunately, you'd need to use a custom TreeView class to work around this. Something like this works:

public class MyTreeView : TreeView {
    protected override void OnKeyDown(KeyEventArgs e) {
        if ((Keyboard.Modifiers & ModifierKeys.Shift) != 0 && e.Key == Key.Tab)
            return;

        base.OnKeyDown(e);
    }
}