<PackageReference Include="NETStandard.Library" Version="2.0.3" />

System.ComponentModel.Design.StandardToolWindows

public class StandardToolWindows
namespace System.ComponentModel.Design { public class StandardToolWindows { public static readonly Guid ObjectBrowser; public static readonly Guid OutputWindow; public static readonly Guid ProjectExplorer; public static readonly Guid PropertyBrowser; public static readonly Guid RelatedLinks; public static readonly Guid ServerExplorer; public static readonly Guid TaskList; public static readonly Guid Toolbox; public StandardToolWindows(); } }