On Saturday, 10 September 2022 at 10:39:12 UTC, Injeckt wrote: > server.d(29): Error: function `server.WndProc(void* hwnd, uint > message, uint wParam, int lParam)` is not callable using > argument types `()` I think you need to get address of a function: ```d wndclass.lpfnWndProc = &WndProc; ```