[DllImportAttribute ( LibNames.User32, CharSet=CharSet.Auto, SetLastError=true ) ]
    public extern RegisterClassEx(wc : WNDCLASSEX) : ushort;

method is marked `extern' but do not have DllImport attribute

    [DllImport( LibNames.User32, CharSet=CharSet.Auto, SetLastError=true ) ]
    public extern RegisterClassEx(wc : WNDCLASSEX) : ushort;

V>спасибо, Кэп Но это не помогает.

[DllImport("user32.dll", CharSet=CharSet.Auto, SetLastError=true)]
public extern RegisterClassExA(wc : WNDCLASSEX) : ushort;

public const string user = "User32.dll";

V>public const string user = "User32.dll";
V>

public static user = "User32.dll";

  module LibNames
  {
    public Activeds = "activeds.dll";
    public Advapi32 = "advapi32.dll";
    public Comctl32 = "comctl32.dll";
    public Comdlg32 = "comdlg32.dll";
    public DwmAPI = "dwmapi.dll";
    public Gdi32 = "gdi32.dll";
    public Gdiplus = "gdiplus.dll";
    public Hhctrl = "hhctrl.ocx";
    public Imm32 = "imm32.dll";
    public Kernel32 = "kernel32.dll";
    public Loadperf = "Loadperf.dll";
    public Mqrt = "mqrt.dll";
    public Mscoree = "mscoree.dll";
    public MsDrm = "msdrm.dll";
    public Mshwgst = "mshwgst.dll";
    public Msi = "msi.dll";
    public NaturalLanguage6 = "naturallanguage6.dll";
    public Ntdll = "ntdll.dll";
    public Ole32 = "ole32.dll";
    public Oleacc = "oleacc.dll";
    public Oleaut32 = "oleaut32.dll";
    public Olepro32 = "olepro32.dll";
    public Penimc = "penimc.dll";
    public Psapi = "psapi.dll";
    public Shell32 = "shell32.dll";
    public Shfolder = "shfolder.dll";
    public Urlmon = "urlmon.dll";
    public User32 = "user32.dll";
    public Uxtheme = "uxtheme.dll";
    public Version = "version.dll";
    public Vsassert = "vsassert.dll";
    public Wininet = "wininet.dll";
    public Winmm = "winmm.dll";
    public Winspool = "winspool.drv";
  }