Ah, I see what you mean now. But the context is a Win32 app that is very deliberately written in C, so my take was from that perspective - i.e. there's no good reason to avoid .rc files and instead handwrite CreateWindow, handle DPI etc in this case.
However, even in the case that you describe, you don't actually have to use a resource DLL. CreateDialogIndirect can be used to create a dialog from an array of DLGITEMTEMPLATE structs, each describing a single control. I'm not entirely sure, but I suspect that compiled dialogs are basically just a dump of that array (but if not you could always just create it manually).
However, even in the case that you describe, you don't actually have to use a resource DLL. CreateDialogIndirect can be used to create a dialog from an array of DLGITEMTEMPLATE structs, each describing a single control. I'm not entirely sure, but I suspect that compiled dialogs are basically just a dump of that array (but if not you could always just create it manually).