OnlineMonitorSystem/HandyControl/HandyControl_Shared/Themes/Styles/Base/DrawerBaseStyle.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="DrawerBaseStyle" TargetType="hc:Drawer">
        <Setter Property="Dock" Value="Right"/>
        <Setter Property="MaskBrush" Value="{DynamicResource DarkOpacityBrush}"/>
    </Style>

</ResourceDictionary>