WPF Ribbon steals TAB - wpf

Question

I have a simple WPF application with Ribbon and few controls. Unfortunately when pressing TAB key to change focus, Ribbon somehow manages looping only within itself, other controls don't get a chance...
This is the XAML:
<Window x:Class="WpfApplication4.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:my="http://schemas.microsoft.com/winfx/2006/xaml/presentation/ribbon"
Title="MainWindow" Height="350" Width="525" >
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="136" />
<RowDefinition Height="175*" />
</Grid.RowDefinitions>
<my:Ribbon HorizontalAlignment="Stretch" Name="ribbon1" VerticalAlignment="Top">
<my:RibbonTab Header="Ribbon">
<my:RibbonGroup>
<my:RibbonComboBox Label="ComboBox" Name="ribbonComboBox1">
<my:RibbonGallery MaxColumnCount="1">
<my:RibbonGalleryCategory>
<my:RibbonGalleryItem Content="An item" />
</my:RibbonGalleryCategory>
</my:RibbonGallery>
</my:RibbonComboBox>
</my:RibbonGroup>
</my:RibbonTab>
</my:Ribbon>
<TextBox TabIndex="1" Grid.Row="1" Height="23" HorizontalAlignment="Left" Margin="12,19,0,0" Name="textBox1" VerticalAlignment="Top" Width="120" />
<TextBox TabIndex="2" Height="23" HorizontalAlignment="Left" Margin="12,48,0,0" Name="textBox2" VerticalAlignment="Top" Width="120" Grid.Row="1" />

Answer 1

OK. Let me answer myself. For my purposes it's OK to NOT to use TAB for Ribbon. For Ribbon I can use KeyTip(s), so basically I have just added Focusable="False" KeyboardNavigation.TabNavigation="None" into ribbon definition. So the whole code could look like this:
<Window x:Class="WpfApplication4.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:my="http://schemas.microsoft.com/winfx/2006/xaml/presentation/ribbon"
Title="MainWindow" Height="350" Width="525" >
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="136" />
<RowDefinition Height="175*" />
</Grid.RowDefinitions>
<my:Ribbon Focusable="False" KeyboardNavigation.TabNavigation="None" HorizontalAlignment="Stretch" Name="ribbon1" VerticalAlignment="Top">
<my:RibbonTab Header="Ribbon" KeyTip="R">
<my:RibbonGroup>
<my:RibbonComboBox KeyTip="C" Label="ComboBox" Name="ribbonComboBox1">
<my:RibbonGallery MaxColumnCount="1">
<my:RibbonGalleryCategory>
<my:RibbonGalleryItem Content="An item" />
</my:RibbonGalleryCategory>
</my:RibbonGallery>
</my:RibbonComboBox>
</my:RibbonGroup>
</my:RibbonTab>
</my:Ribbon>
<TextBox TabIndex="1" Grid.Row="1" Height="23" HorizontalAlignment="Left" Margin="12,19,0,0" Name="textBox1" VerticalAlignment="Top" Width="120" />
<TextBox TabIndex="2" Height="23" HorizontalAlignment="Left" Margin="12,48,0,0" Name="textBox2" VerticalAlignment="Top" Width="120" Grid.Row="1" />
</Grid>
</Window>

Answer 2

KeyboardNavigation.TabNavigation="Continue" does it for me, using System.Windows.Controls.Ribbon.dll