新增或修改時 設置顯示的默認值

public class DemoTask : Task {
    // ...
    private Priority priority;
    public Priority Priority {
        get { return priority; }
        set {
            SetPropertyValue("Priority", ref priority, value);
        }
    }
    //...
}
public enum Priority {
    Low = 0,
    Normal = 1,
    High = 2
}



[DefaultClassOptions]
[Custom("Caption", "Task")]
public class DemoTask : Task {
    //...
    public override void AfterConstruction() {
        base.AfterConstruction();
        Priority = Priority.Normal;
    }
    //...
}