using Microsoft . Win32;

using System . Runtime . InteropServices;

[ DllImport ( "shell32.dll" , CharSet = CharSet . Auto, SetLastError = true)]

internal static extern void SHChangeNotify( uint wEventId , uint uFlags ,

    IntPtr dwItem1, IntPtr dwItem2);

private const uint SHCNE_ASSOCCHANGED = 0x08000000 ;

private const uint SHCNF_IDLIST = 0x0000 ;

private const uint SHCNF_FLUSH = 0x1000 ;

private void UnregistryShell()

{

   registryShell = false ;

    bool changeRegistry = false ;

    RegistryKey vRegistryKey = Registry . ClassesRoot . OpenSubKey( ".xxx" );

    if (vRegistryKey != null )

   {

       changeRegistry = true ;

       vRegistryKey . Close();

        Registry . ClassesRoot . DeleteSubKeyTree( ".xxx" );

   }

   vRegistryKey = Registry . ClassesRoot . OpenSubKey( "xxx Document" );

    if (vRegistryKey != null )

   {

       changeRegistry = true ;

       vRegistryKey . Close();

        Registry . ClassesRoot . DeleteSubKeyTree( "xxx Document" );

   }

    if (changeRegistry)

       SHChangeNotify(SHCNE_ASSOCCHANGED, SHCNF_IDLIST | SHCNF_FLUSH,

            IntPtr . Zero, IntPtr . Zero);

}

private bool IsRegistryShell()

{

    RegistryKey vRegistryKey = Registry . ClassesRoot . OpenSubKey( ".xxx" );

    if (vRegistryKey == null ) return false ;

   vRegistryKey = Registry . ClassesRoot . OpenSubKey(

        @"xxx Document\shell\open\command" );

    if (vRegistryKey == null) return false ;

    if (vRegistryKey . GetValue( "" ) . ToString() . ToLower() !=

        Application . ExecutablePath . ToLower() + " \"%1\"" ) return false ;

    return true ;

}

//

private void Form1_Load( object sender , EventArgs e)

{

    string [] vCommands = Environment . GetCommandLineArgs();

    if (vCommands . Length > 1 )

   {

       OpenDocument(vCommands[ 1 ]);

   }

}