FPGACoder/HandyControl/HandyControl_Shared/Themes/Styles/Base/DialogBaseStyle.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:hc="clr-namespace:HandyControl.Controls">

    <Style x:Key="DialogBaseStyle" TargetType="hc:Dialog">
        <Setter Property="Focusable" Value="False"/>
        <Setter Property="HorizontalContentAlignment" Value="Center"/>
        <Setter Property="VerticalContentAlignment" Value="Center"/>
        <Setter Property="MaskBrush" Value="{DynamicResource DarkOpacityBrush}"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="hc:Dialog">
                    <Border x:Name="PART_BackElement" Background="{TemplateBinding MaskBrush}">
                        <ContentPresenter Margin="{TemplateBinding Padding}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

</ResourceDictionary>