外部设置UI上control的Visibility

　　外部设置UI上control的Visibility，一般会在property里进行设置，例如：
        

public Visibility CancelButtonVisibility{
           get{
                    return this.btnCancel.Visibility;
            }
            set{
                  this.btnCancel.Visibility = value;
            }
}

     这样在property中直接拿control不太好。有另一种方法会好点：

private Boolean _isCancellable = false;

//Get/Set IsCancellable property
public Boolean IsCancellable{
       get{
             return this._isCancellable;
        }
        set{
              this._isCancellable = value;
              this.OnIsCancellableChanged();
        }
}

protected virtual void OnIsCancellableChanged() {
     if(this.IsCancellable){
            this.btnCancel.Visibility = Visibility.Visible;
     }else{
            this.btnCancel.Visibility = Visibility.Collapsed;
     }
}