我试图更改自定义控件矩形的背景颜色。如果我的属性（bool）为setSelected==true，则颜色应为Red。如果为setSelected==false，则颜色应为Transparent。
如何更改Rectangle的装订背景颜色？
通用：

<Style TargetType="{x:Type local:IdnStatusRect}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type local:IdnStatusRect}">
                <Border Background="Transparent"
                        BorderBrush="Purple"
                        BorderThickness="0">
                    <DockPanel HorizontalAlignment="Center" VerticalAlignment="Center" Width="15" Height="15" Background="Transparent">
                        <Grid>
                            <Rectangle Width="15" Height="15" Fill="Transparent" Stroke="#97CDEB" StrokeThickness="1"/>
                            <Grid.Background>
                                <LinearGradientBrush StartPoint="0.5,0" EndPoint="0.5,1">
                                    <GradientStop Color="{Binding Path=BackgroundColor, RelativeSource={RelativeSource TemplatedParent}}" Offset="0" />

                                </LinearGradientBrush>

                            </Grid.Background>

                        </Grid>
                    </DockPanel>
                </Border>

            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

状态矩形：

public class IdnStatusRect : Control
{
    public bool setSelected
    {
        get { return (bool)GetValue(setSelectedPropert); }
        //  set { SetValue(RectPropert1, Application.Current.FindResource(value.ToString())); }
        set { SetValue(setSelectedPropert, value); }
    }
    
    public static readonly DependencyProperty setSelectedPropert =
        DependencyProperty.Register("setSelected", typeof(bool), typeof(IdxButton), new UIPropertyMetadata(false));

    public Color BackgroundColor
    {
        get { return (Color)GetValue(setSelectedPropert); }
        set { SetValue(BackgroundColorProperty, FindResource("TextColor1")); }
    }

    public static readonly DependencyProperty BackgroundColorProperty =
                DependencyProperty.Register("BackgroundColor", typeof(Color), typeof(IdxButton), new PropertyMetadata((sender, args) => {
                    System.Diagnostics.Debug.WriteLine("Set bg col");
                }));

    static IdnStatusRect()
    {
        DefaultStyleKeyProperty.OverrideMetadata(typeof(IdnStatusRect), new FrameworkPropertyMetadata(typeof(IdnStatusRect)));
    }