How to create a desktop shortcut (link), but with own shortcut file extension (e.g. .appfolder) instead of .lnk programmatically in C#?

I have registered a shortcut file extension named .appfolder in registry: reg export

It should behave like a normal .lnk shortcut, but has to have .appfolder ending (that has it reasons).

Now I want to create an shortcut with that file ending/extension programmatically in C#. Default for .lnk ending it works with:

public static void CreateShortcut(string shortcutName, string shortcutPath, string targetFileLocation)
    {
        string shortcutLocation = Path.Combine(shortcutPath, shortcutName + @".lnk");
        WshShell shell = new WshShell();
        IWshShortcut shortcut = (IWshShortcut)shell.CreateShortcut(shortcutLocation);
        shortcut.Description = "My shortcut description";
        shortcut.TargetPath = targetFileLocation;                 
        shortcut.Save();
    }

//e.g:
CreateShortcut("Example (Notepad)", Environment.GetFolderPath(Environment.SpecialFolder.Desktop),
                "notepad.exe");

When I try to change file extension in this line string shortcutLocation = Path.Combine(shortcutPath, shortcutName + @".lnk"); to .appfolder I get an System.Runtime.InteropServices.COMException (HRESULT: 0x80020009 (DISP_E_EXCEPTION)).

When I try to change file extension after creating/saving shortcut with File.Move(shortcutLocation, Path.ChangeExtension(shortcutLocation, ".appfolder")); I get an file on desktop with following properties: image

As you can see Windows does recognize .appfolder extension as shortcut, but the 'Shortcut' tab is missing and when I double-click the file to execute, it happens nothing.

So, either my registration of .appfolder is not complete right, although it should be... or how to create a shortcut with own shortcut file extension programmatically in C#?

Thanks for help ;)

EDIT :

I tried another way to create the shortcut programatically:

void main() {
    IShellLink link = (IShellLink)new ShellLink();

    // setup shortcut information
    link.SetDescription("My Description");
    link.SetPath(@"notepad.exe");

    // save it
    IPersistFile file = (IPersistFile)link;
    string desktopPath = Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory);
    file.Save(Path.Combine(desktopPath, "Notepad.appfolder"), false);
}

    [ComImport]
    [Guid("00021401-0000-0000-C000-000000000046")]
    internal class ShellLink
    {
    }

    [ComImport]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    [Guid("000214F9-0000-0000-C000-000000000046")]
    internal interface IShellLink
    {
        void GetPath([Out, MarshalAs(UnmanagedType.LPWStr)] StringBuilder pszFile, int cchMaxPath, out IntPtr pfd, int fFlags);
        void GetIDList(out IntPtr ppidl);
        void SetIDList(IntPtr pidl);
        void GetDescription([Out, MarshalAs(UnmanagedType.LPWStr)] StringBuilder pszName, int cchMaxName);
        void SetDescription([MarshalAs(UnmanagedType.LPWStr)] string pszName);
        void GetWorkingDirectory([Out, MarshalAs(UnmanagedType.LPWStr)] StringBuilder pszDir, int cchMaxPath);
        void SetWorkingDirectory([MarshalAs(UnmanagedType.LPWStr)] string pszDir);
        void GetArguments([Out, MarshalAs(UnmanagedType.LPWStr)] StringBuilder pszArgs, int cchMaxPath);
        void SetArguments([MarshalAs(UnmanagedType.LPWStr)] string pszArgs);
        void GetHotkey(out short pwHotkey);
        void SetHotkey(short wHotkey);
        void GetShowCmd(out int piShowCmd);
        void SetShowCmd(int iShowCmd);
        void GetIconLocation([Out, MarshalAs(UnmanagedType.LPWStr)] StringBuilder pszIconPath, int cchIconPath, out int piIcon);
        void SetIconLocation([MarshalAs(UnmanagedType.LPWStr)] string pszIconPath, int iIcon);
        void SetRelativePath([MarshalAs(UnmanagedType.LPWStr)] string pszPathRel, int dwReserved);
        void Resolve(IntPtr hwnd, int fFlags);
        void SetPath([MarshalAs(UnmanagedType.LPWStr)] string pszFile);
    }

It creates the shortcut file without any error (like System.Runtime.InteropServices.COMException, see above), but it doesn't execute the .exe file by double-clicking neither.

I solved it: My registration of .appfolder wasn't completely correct to work exactly like .lnk shortcut file. Follow this instruction. After that both methods in C# mentioned above work.