How to add dialog & menu to Win32 DLL?

The way to it is quite different than MFC. Here is an example I have written for creating a simple DLL with a dialog and two buttons "Exit" and "Say Hi", It may looks complex but it's really simple,:

// DllDialog.cpp
#define _WIN32_WINNT 0x0501
#define WIN32_LEAN_AND_MEAN

#include "stdafx.h"
#include <windows.h>

#define MESSAGE_MAP(MessageParam, MessageCallback)\
    if(message == MessageParam)\
        return MessageCallback(hwnd, message, wParam, lParam)

#define MESSAGE_MAP_COMMAND(Identifier, MessageCallback)\
    if((message == WM_COMMAND) && (LOWORD(wParam) == Identifier))\
    return MessageCallback(hwnd, message, wParam, lParam);

#define IDD_DIALOGBOX    101
#define IDD_BUTTON_EXIT  1001
#define IDD_BUTTON_SAYHI 1002

#define DllExport  __declspec(dllexport)
#define STDCALL    __cdecl

#if __cplusplus
extern "C" {
#endif

DllExport INT_PTR STDCALL StartDialog(VOID);

#if __cplusplus
};
#endif

// FIXME: There is a better way by passing the hInstance as a parameter to StartDialog
HINSTANCE hInstance = 0;

BOOL CALLBACK DialogProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam);

BOOL OnDialogInit(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam);
BOOL OnDialogDestroy(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam);
BOOL OnDialogClose(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam);

BOOL OnDialogButtonExitClicked(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam);
BOOL OnDialogButtonSayHiClicked(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam);

BOOL APIENTRY DllMain(HMODULE hModule, DWORD  ul_reason_for_call, LPVOID lpReserved)
{
    if(ul_reason_for_call == DLL_PROCESS_ATTACH)
        hInstance = (HINSTANCE) hModule;
    return TRUE;
}

INT_PTR StartDialog(VOID)
{
    return DialogBox(hInstance, MAKEINTRESOURCE(IDD_DIALOGBOX), NULL, DialogProc);
}

BOOL CALLBACK DialogProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    MESSAGE_MAP(WM_INITDIALOG, OnDialogInit);
    MESSAGE_MAP(WM_DESTROY, OnDialogDestroy);
    MESSAGE_MAP(WM_CLOSE, OnDialogClose);

    MESSAGE_MAP_COMMAND(IDD_BUTTON_EXIT, OnDialogButtonExitClicked);
    MESSAGE_MAP_COMMAND(IDD_BUTTON_SAYHI, OnDialogButtonSayHiClicked);

    return FALSE;
}

BOOL OnDialogInit(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    return TRUE;
}

BOOL OnDialogDestroy(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    PostQuitMessage(0);
    return TRUE;
}

BOOL OnDialogClose(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    DestroyWindow(hwnd);
    return TRUE;
}

BOOL OnDialogButtonExitClicked(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    OnDialogClose(hwnd, message, wParam, lParam);
    return TRUE;
}

BOOL OnDialogButtonSayHiClicked(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    MessageBox(hwnd, TEXT("Hi :D!"), TEXT("DLL"), MB_OK);
    return TRUE;
}

• Open Visual Stdio, I'm using VS2005, and create a new C++ DLL project named, for example, DllDialog.
• Add a new resource file by right clicking on the Resource Files and then
• Add > New Item. Choose from Resource the Resource Files and name it what ever you like, for example, resource.rc.
• Go to the resource view and right click on the resource file you've just created and choose Add Resource ... and click on the dialog icon and click new.
• You should see a dialog with two buttons, "OK" and "Cancel"; delete them and add two new buttons, "Exit" and "Say Hi". From the propitiates change the ID of the button "Exit" to IDD_BUTTON_EXIT and IDD_BUTTON_SAYHI for "Say Hi".
• Find out the value of this IDs, just right click on resource.rc and choose Resource Symbols.

Make sure you change these definitions so they match yours:

#define IDD_DIALOGBOX    101
#define IDD_BUTTON_EXIT  1001
#define IDD_BUTTON_SAYHI 1002

That code is a DLL that exports a function named StartDialog, you could test it by including this header file in your application:

// header.h
#ifndef __HEADER_H__
#define __HEADER_H__

#include <windows.h>

#define STDCALL    __cdecl
typedef INT_PTR (STDCALL *StartDialogFunc)(VOID);

#endif /* __HEADER_H__ */

and call that using dynamic loading for example:

// foo.cpp
#define _WIN32_WINNT 0x0501
#define WIN32_LEAN_AND_MEAN

#include <windows.h>
#include "header.h"

INT WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
{
    HMODULE hDll;
    StartDialogFunc StartDialog;

    hDll = LoadLibrary(TEXT("DllDialog.dll"));
    if(!hDll) {
        MessageBox(NULL, TEXT("Cannot load DllDialog.dll"), NULL, MB_OK);
        return -1;
    }

    StartDialog = (StartDialogFunc) GetProcAddress(hDll, "StartDialog");

    StartDialog();

    return 0;
}

I hope this is helpful.

Good luck.