https://www.2cto.com/kf/201302/188246.html
https://blog.csdn.net/bychentufeiyang/article/details/7081402
[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
Winform自定义控件添加复杂属性（struct,class等）
原文：https://www.cnblogs.com/lihuali/p/10688228.html