<Grid Background="Transparent" Margin="0,0,0,0" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Grid.RowDefinitions>
        <RowDefinition Height="*"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="150"/>
        <ColumnDefinition Width="Auto"/>
    </Grid.ColumnDefinitions>

    <TextBox Name="tbmain" Grid.ColumnSpan="2" Grid.RowSpan="2"
                Text="" 
                Margin="0,0,0,0" />

    <RepeatButton Name="PART_UpButton" BorderThickness="0" Grid.Column="1" Grid.Row="0"
                    Width="13" Background="Transparent">
        <Path Fill="Black" Data="M 0 3 L 6 3 L 3 0 Z"/>
    </RepeatButton>
    <RepeatButton Name="PART_DownButton" BorderThickness="0" Grid.Column="1" Grid.Row="1"
                    Width="13" Background="Transparent">
        <Path Fill="Black" Data="M 0 0 L 3 3 L 6 0 Z"/>
    </RepeatButton>

</Grid>