I'm using Rider 2019.3 on Windows 10. I have a dotNet Framework 4.7.1 Class library project using System.Windows.Forms.
When switching to Rider i have encountered the problem, that i can't open all of my WinForms in the integrated designer. I can't find information about under which circumstances the designer recognizes WinForms. Both files I'm comparing right now, of which one is working fine, while the other is not, inherit from System.Windows.Forms.Form.