Dump the list of Shell Icon Overlay Identifiers

ShellIconOverlayIdentifiers.cs

static void Main()
{
    using (var key = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\ShellIconOverlayIdentifiers", false))
    {
        foreach (var name in key.GetSubKeyNames())
        {
            Console.WriteLine("'" + name + "'");
            using (var sub = key.OpenSubKey(name, false))
            {
                if (!(sub.GetValue(null) is string def) || !Guid.TryParse(def, out var clsid))
                    continue;

                Console.WriteLine(" clsid:" + clsid);
                var type = Type.GetTypeFromCLSID(clsid, false);
                if (type == null)
                    continue;

                IShellIconOverlayIdentifier identifier;
                try
                {
                    identifier = Activator.CreateInstance(type) as IShellIconOverlayIdentifier;
                }
                catch
                {
                    continue;
                }

                var sb = new StringBuilder(256);
                if (identifier.GetOverlayInfo(sb, sb.Capacity, out var index, out var flags) >= 0)
                {
                    identifier.GetPriority(out var priority);
                    Console.WriteLine(" index: " + index + " flags: " + flags + " priority: " + priority + " icon:" + sb);
                    Console.WriteLine();
                }
            }
        }
    }
}

[ComImport, Guid("0c6c4200-c589-11d0-999a-00c04fd655e1"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
private interface IShellIconOverlayIdentifier
{
    [PreserveSig]
    int IsMemberOf(string pwszPath, int dwAttrib);

    [PreserveSig]
    int GetOverlayInfo(StringBuilder pwszIconFile, int cchMax, out int pIndex, out ISIOI pdwFlags);

    [PreserveSig]
    int GetPriority(out int pPriority);
}

[Flags]
private enum ISIOI
{
    ISIOI_NONE = 0,
    ISIOI_ICONFILE = 1,
    ISIOI_ICONINDEX = 2,
}