SHJX_GM/SHJX.Service.WorkFlowEdit/themes/RectPort.xaml

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:c="clr-namespace:SHJX.Service.WorkFlowEdit">

    <ResourceDictionary.MergedDictionaries>
        <ResourceDictionary Source="/SHJX.Service.WorkFlowEdit;component/Themes/Shared.xaml" />
    </ResourceDictionary.MergedDictionaries>

    <Style TargetType="{x:Type c:RectPort}">
        <Setter Property="SnapsToDevicePixels" Value="true" />
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate>
                    <Rectangle
                        Fill="LightBlue"
                        Stroke="Black"
                        StrokeThickness="1" />
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>