I just installed VS2019 and can't figure out why most of the Toolbox components are disabled, only 'All Windows Forms' can be used.
According to https://devblogs.microsoft.com/dotnet/introducing-net-core-windows-forms-designer-preview-1/
are not supported in the .Net Core 3.0 Designer yet
You have to use the .Net Framework (newest Version is 4.7.2) until these things get added to .Net Core