Writing your Custom Control: step by step
https://www.codeproject.com/Articles/2016/Writing-your-Custom-Control-step-by-step
https://www.c-sharpcorner.com/UploadFile/ehtesham.dotnet/how-to-create-a-custom-control/
https://stackoverflow.com/questions/6405458/how-do-i-make-custom-controls-in-c
