[MissionPlanner DEV] Cannot design new User Control


I would like to create new control for Mission Planner. Now the strange thing happens - when I add new user control (in MissionPlanner.Controls) I cannot open the designer for it. I cannot neither open HUD.cs in designer for example. I am using VS Community 2017. Did anybody come across this issue?

Thank you for your help

the hud us not a user designed control. it is a dynamically rendered control. ie all code