show windows 3.1 file open dialog

fileopen.c

// this program opens an old win 3.1 file-open dialog.
//
// it works if OFN_EXPLORER is missing AND a hook is used.
//
// compile with msys2/mingw:
//  gcc fileopen.c -lcomdlg32 -o fileopen
#include<windows.h>
#include<commdlg.h>
#include<stdio.h>

UINT_PTR CALLBACK hook(_In_ HWND hdlg, _In_ UINT uiMsg, _In_ WPARAM wParam, _In_ LPARAM lParam){ return 0; }


int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow){
 OPENFILENAME ofn;
 char szFile[260];
 HWND hwnd=NULL;
 
 ZeroMemory(&ofn, sizeof(ofn));
 ofn.lStructSize = sizeof(ofn);
 ofn.hwndOwner = hwnd;
 ofn.lpstrFile = szFile;
 ofn.lpstrFile[0] = '\0';
 ofn.nMaxFile = sizeof(szFile);
 ofn.lpstrFilter = "All\0*.*\0Text\0*.TXT\0";
 ofn.nFilterIndex = 1;
 ofn.lpstrFileTitle = NULL;
 ofn.nMaxFileTitle = 0;
 ofn.lpstrInitialDir = NULL;
 ofn.lpfnHook = hook;
 ofn.Flags = OFN_PATHMUSTEXIST | OFN_FILEMUSTEXIST | OFN_ENABLEHOOK ;
 
 
 if (GetOpenFileName(&ofn)) 
  printf("%s\n", ofn.lpstrFile);
 return 0;
}