Resizing Docker Width

I am trying to create a docker that is a strip with squared buttons, but I am not able to change the docker width...I have no idea of how to change this, have anyone faced the same problem before?

The docker xaml code is currently like this:

<UserControl x:Class="Dea_Tools.DockerUI"
             xmlns="">schemas.microsoft.com/.../presentation"
             xmlns:x="">schemas.microsoft.com/.../xaml"
             xmlns:mc="">schemas.openxmlformats.org/.../2006"
             xmlns:d="">schemas.microsoft.com/.../2008"
             xmlns:local="clr-namespace:Dea_Tools"
             mc:Ignorable="d"
             MinWidth="60" Loaded="UserControl_Loaded">
    <UserControl.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="Styles/Colors.xaml"/>
                <ResourceDictionary Source="Styles/Styles.xaml"/>
                <ResourceDictionary Source="Resources/Images.xaml"/>
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </UserControl.Resources>
    <Grid Margin="0,0,0,0" Width="60">
        <StackPanel Width="60" Height="220" HorizontalAlignment="Center">
            <Button x:Name="button1" Content="" Click="numAutomatico" Height="40" HorizontalAlignment="Center" Width="40" Margin="0,10,0,0">
            <Button x:Name="button2" Content="" Click="expCurvas" Margin="0,10,0,0" Width="40" Height="40" HorizontalAlignment="Center">
            <Button x:Name="button3" Content="" Click="cotaAutomatica" Margin="0,10,0,0" Width="40" Height="40" HorizontalAlignment="Center">
            <Button x:Name="button4" Content="Cota Alinhada (Beta)" Click="cotaAlinhada" Margin="0,10,0,0" Width="40" Height="40" HorizontalAlignment="Center"/>
        </StackPanel>
    </Grid>
</UserControl>

Thanks!