C# WPF .NET 4.0 ArrowRepeatButton, NumericUpDown, and TimeCtrl Controls

<UserControl x:Class="UpDownCtrls.TimeCtrl"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d" 
             xmlns:local="clr-namespace:UpDownCtrls"
             x:Name="Root"
             d:DesignHeight="23" d:DesignWidth="120"
             Loaded="Root_Loaded"
             MouseLeftButtonDown="Root_MouseLeftButtonDown"
             MouseRightButtonDown="Root_MouseRightButtonDown"
             IsEnabledChanged="Root_IsEnabledChanged"
             FocusManager.IsFocusScope="True">
<!-- Unfortunately, having the line above "FocusManager.IsFocusScope="True"" causes a problem: the selection in light blue sometimes becomes 
    invisible when right click and menu appears. This looks to me like a Microsoft bug, and I feel light blue selection should always remain
    visible. 
If desperate for selection to always display, remove this line and modify GetTextBoxToFocusOn function, so it no longer uses FocusManager. 
    A simple solution would be to simply traverse all items in TimeCtrls grid until find a item which has focus. The drawback of this solution
    is control will no longer keep in memory last item which had focus. To overcome that, you might have a member variable ‘int LastItemFocused’,
    which keeps track of index of last focused item and use that variable when appropriate (that is no items in TimeCtrls currently have focus). -->
    <UserControl.Resources>
        <ContextMenu x:Key="HiddenContextMenu" Visibility="Hidden"/>
    </UserControl.Resources>
    <Grid>
        <TextBox Name="TextBoxCtrl" VerticalAlignment="Stretch" Padding="2,2,18,2" 
                IsEnabled="{Binding IsEnabled, ElementName=Root}"               
                Foreground="{Binding Foreground, ElementName=Root}" 
                Background="{Binding Background, ElementName=Root}" 
                Height="{Binding ActualHeight, ElementName=Root}"
                Width="{Binding ActualWidth, ElementName=Root}"
                VerticalContentAlignment="{Binding VerticalContentAlignment, ElementName=Root}"
                HorizontalContentAlignment="{Binding  HorizontalContentAlignment, ElementName=Root}" Focusable="False"
                ContextMenu="{StaticResource HiddenContextMenu}"
                PreviewDragEnter="tb_PreviewDrag"
                PreviewDragOver="tb_PreviewDrag">
            <TextBox.CommandBindings>
                <CommandBinding Command="Cut" CanExecute="CommandBinding_CanExecute"/>
                <CommandBinding Command="Paste" CanExecute="CommandBinding_CanExecute"/>
            </TextBox.CommandBindings>
        </TextBox>
        <Grid Name="TimeCtrls" Style="{DynamicResource ResourceKey=TimeCtrlsGridStyle}"/>
        <local:UpDownButtons x:Name="UpDown" HorizontalAlignment="Right" 
                Style="{DynamicResource ResourceKey=UpDownButtonsStyle}" 
                VerticalAlignment="Stretch" IsEnabled="{Binding IsEnabled, ElementName=Root}"
                UpClick="UpDown_UpClick" DownClick="UpDown_DownClick"/>
        <Popup Name="ValidTimesPopup" IsOpen="False" StaysOpen="False" PlacementTarget="{Binding ElementName=TextBoxCtrl}" Placement="Bottom">
            <Border BorderBrush="#FF7F9DB9" BorderThickness="1" Background="{Binding Background, ElementName=Root}">
                <Grid Name="ValidTimesGrid" Background="{Binding Background, ElementName=Root}"/>
            </Border>
        </Popup>
    </Grid>
</UserControl>