Thread: Dialog Double Up

I'm diving into the WinAPI and have completed a simple dialog. When I run the application the dialog is drawn twice and mostly on top of itself. I can't determine what is causing this duplication.

Code:

#include <Windows.h>
#include "resource.h"


const char g_szClassName[] = "myWindowClass";


BOOL CALLBACK AboutDlgProc(HWND hwnd, UINT dMsg, 
    WPARAM wParam, LPARAM lParam)
{
    switch (dMsg)
    {
    /*Dialog preprocessing*/
    case WM_INITDIALOG:
        
        return TRUE; //set keyboard focus to default control
        break;
    case WM_COMMAND:
        switch (wParam)
        {
        case IDD_HELP_ABOUT_OK:
            EndDialog(hwnd, IDD_HELP_ABOUT_OK);
            break;
        }
        break;
    default:
        return TRUE;
    }
    return TRUE;
}


LRESULT CALLBACK WndProc(HWND hwnd, UINT wMsg, WPARAM wParam, LPARAM lParam)
{
    switch (wMsg)
    {
    /*Window Preprocessing*/
    case WM_CREATE:
        
        break;


    case WM_COMMAND:
        switch (wParam)
        {
        case IDMI_FILE_EXIT:
            DestroyWindow(hwnd);
            break;
        case IDMI_HELP_ABOUT:
            DialogBox(GetModuleHandle(NULL), MAKEINTRESOURCE(IDD_HELP_ABOUT),
                hwnd, (DLGPROC)AboutDlgProc);
            break;
        }


    /*Clean up and call destroy*/
    case WM_CLOSE:
        DestroyWindow(hwnd);
        break;


    /*Destroy Window*/
    case WM_DESTROY:
        PostQuitMessage(0);
        break;


    default:
        return DefWindowProc(hwnd, wMsg, wParam, lParam);
        break;
    }
    return 0;
}


int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE HPrevInstance,
    LPSTR lpCmdLine, int nCmdShow)
{
    WNDCLASSEX wc;
    HWND hwnd;
    MSG wMsg;


    //Register the Window Class
    wc.cbSize            = sizeof(WNDCLASSEX);
    wc.style            = 0;
    wc.lpfnWndProc        = WndProc;
    wc.cbClsExtra        = 0;
    wc.cbWndExtra        = 0;
    wc.hInstance        = hInstance;
    wc.hIcon            = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor            = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground    = (HBRUSH)(COLOR_WINDOW + 1);
    wc.lpszMenuName        = MAKEINTRESOURCE(IDM_FILE_MENU);
    wc.lpszClassName    = g_szClassName;
    wc.hIconSm            = LoadIcon(NULL, IDI_APPLICATION);


    //Check that the registration was successful
    if (!RegisterClassEx(&wc))
    {
        MessageBox(NULL, "Window Registration Failed!", "Error!",
            MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }


    //Create Window
    hwnd = CreateWindowEx(
        WS_EX_CLIENTEDGE,
        g_szClassName,
        "Toolboxie",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, 256, 128,
        NULL, NULL, hInstance, NULL);


    //Check Window Creation
    if (hwnd == NULL)
    {
        MessageBox(NULL, "Window Creation Failed!", "Error!",
            MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }


    //Draw Window
    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);


    //Message Loop
    while (GetMessage(&wMsg, NULL, 0, 0) > 0)
    {
        TranslateMessage(&wMsg);
        DispatchMessage(&wMsg);
    }


    //End
    return wMsg.wParam;
}

Code:

IDD_HELP_ABOUT DIALOGEX 0, 0, 202, 60
STYLE DS_SETFONT | DS_MODALFRAME | DS_FIXEDSYS | WS_CAPTION
CAPTION "About Toolboxie"
FONT 8, "MS Shell Dlg", 400, 0, 0x1
BEGIN
    DEFPUSHBUTTON   "OK",IDD_HELP_ABOUT_OK,76,39,50,14
    CTEXT           "Toolboxie was created for FUNctionality and edutainment.",IDD_HELP_ABOUT_TEXT,7,15,187,8,NOT WS_GROUP
END