Using MessageBoxIndirect to show message boxes with custom icons

MessageBoxIndirect is a little known API function defined in user32.dll, that lets you customize message boxes just that little bit more (and it’s highly probable that MessageBox itself uses MessageBoxIndirect internally).

Here’s some sample code that shows how you can show a message box with a custom icon :-

MSGBOXPARAMS params = {0};
params.cbSize = sizeof MSGBOXPARAMS;
params.hInstance = hInstance;
params.lpszText = "Hello there";
params.lpszCaption = "Nish";
params.dwStyle = MB_OK | MB_USERICON;
params.dwLanguageId = MAKELANGID(LANG_NEUTRAL,SUBLANG_NEUTRAL);
params.lpszIcon = MAKEINTRESOURCE(IDI_ICON1);
MessageBoxIndirect (&params);

See MSDN for full documentation on MessageBoxIndirect and MSGBOXPARAMS.