OnlineMonitorSystem/HandyControl/HandyControl_Shared/Themes/Styles/SimpleItemsControl.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 TargetType="hc:SimpleItemsControl">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="hc:SimpleItemsControl">
                    <Border Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}">
                        <StackPanel x:Name="PART_Panel" />
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

</ResourceDictionary>