Showing a window from inside a DLL

im trying to show a window from inside of a dll and i am doing it like this

Code:

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int WINAPI CreateWindows(HINSTANCE , HINSTANCE , LPSTR , int);

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Global^

Code:

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CreateWindows(GetModuleHandle(0), NULL, NULL , NULL);

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^calling from a certain part of the dll

Code:

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int WINAPI CreateWindows(HINSTANCE hInstance, HINSTANCE hPrevInstance , LPSTR szCmdLine, int iCmdShow)
{
        char szAppName[] = "tabs";

        MSG msg;
        WNDCLASSEX wc;

        TCITEM tabs;
        INITCOMMONCONTROLSEX iccx;

        wc.style = CS_DBLCLKS;
        wc.lpfnWndProc = WndProc;
        wc.cbSize = sizeof(WNDCLASSEX);
        wc.cbClsExtra = 0;
        wc.cbWndExtra = 0;
        wc.hInstance = hInstance;
        wc.hbrBackground = CreateSolidBrush(GetSysColor(COLOR_3DFACE));
        wc.hIcon = LoadIcon(NULL , IDI_APPLICATION);
        wc.hCursor = LoadCursor(NULL , IDC_ARROW);
        wc.lpszClassName = szAppName;
        wc.lpszMenuName = NULL;

        if(!RegisterClassEx(&wc)) MessageBox(0 , "Error" , "error" , 0);

        iccx.dwSize = sizeof(INITCOMMONCONTROLSEX);
        iccx.dwICC = ICC_TAB_CLASSES;
        InitCommonControlsEx(&iccx);

        hwnd = CreateWindowEx(0 , szAppName , "Logs" ,
                                WS_OVERLAPPEDWINDOW ,
                                CW_USEDEFAULT , CW_USEDEFAULT,
                                CW_USEDEFAULT , CW_USEDEFAULT,
                                NULL , NULL , hInstance , NULL);

        hwndTab = CreateWindowEx(0 , WC_TABCONTROL , NULL,
                                WS_VISIBLE | WS_CHILD | TCS_FIXEDWIDTH ,
                                0 , 0 , 0 , 0 ,
                                hwnd ,
                                NULL ,
                                (HINSTANCE)GetWindowLong(hwnd, GWL_HINSTANCE),
                                NULL);

        UpdateWindow(hwnd);
        ShowWindow(hwnd , SW_SHOW);

        ZeroMemory(&tabs, sizeof(TCITEM));

        tabs.mask=TCIF_TEXT;
        tabs.pszText= "Log";
        tabs.cchTextMax = strlen(tabs.pszText);
        SendMessage(hwndTab, TCM_INSERTITEM, 0, (LPARAM)&tabs);

        tabs.pszText = "Proccessed Packets";
        tabs.cchTextMax = strlen(tabs.pszText);
        SendMessage(hwndTab, TCM_INSERTITEM, 1, (LPARAM)&tabs);
        SendMessage(hwndTab, WM_SETFONT, (WPARAM)GetStockObject(DEFAULT_GUI_FONT), 0);

        while(GetMessage(&msg , NULL , 0 , 0)){
                TranslateMessage(&msg);
                DispatchMessage(&msg);
        }

        return msg.wParam;
}

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the function to do the rest^

the problem is it is not registering the window class, does any one know why this is, im thinking it is because i am using NULL's in the function parameters but i couldnt think of another way,

thanks