您已正确识别问题的原因：因为R，G，B不是依赖属性，所以即使它们的值改变了，其他控件也不知道。2所以你需要自己实现这些通知。3有几种方法可以做到这一点：

**选项a）**为每个颜色分量（R、G、B）创建单独的DependencyProperty，并在这些属性的PropertyChanged回调中更新ActiveBrush。

public static DependencyProperty RComponentProperty = DependencyProperty.Register("RComponent", typeof(byte), typeof(YorWindow), new PropertyMetadata(0, OnColorComponentChanged)); 
   public static DependencyProperty GComponentProperty = DependencyProperty.Register("GComponent", typeof(byte), typeof(YorWindow), new PropertyMetadata(0, OnColorComponentChanged)); 
   public static DependencyProperty bComponentProperty = DependencyProperty.Register("BComponent", typeof(byte), typeof(YorWindow), new PropertyMetadata(0, OnColorComponentChanged)); 
   private static void OnColorComponentChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
   {
        YorWindow @this = (YorWindow)d;
        Color activeColor = Color.FromRGB(@this.RComponent, @this.GComponent, @this.BComponent);
        d.SetCurrentValue(ActiveBrushProperty, new SolidColorBrush(activeColor));
   }

在ActiveBrushProperty的OnPropertyChanged回调中执行相反的操作-更新所有颜色组件属性。
顺便说一句，你不应该在FrameworkElement上注册依赖属性，使用你的类的类型来声明属性。

class YourClass
{
    public static DependencyProperty ActiveBrushProperty = DependencyProperty.Register("ActiveBrush", typeof(SolidColorBrush), typeof(YourClass)); 
}

**选项B）**使用带有INotifyPropertyChanged的视图模型

public byte RComponent 
{
   get => ActiveBrush.Color.R;
   set 
   {
      if(value != ActiveBrush.Color.R)
      {
          ActiveBrush.Color.R = value;
          RaisePropertyChanged(nameof(RComponent));
          RaisePropertyChanged(nameof(ActiveBrush));
      }
   }
}

**选项c）**实现IValueConverter以将Brush转换为单个组件，并在绑定到Slider时使用它。