fpc demo_window.pas 
Free Pascal Compiler version 3.2.2+dfsg-51 [2026/07/09] for x86_64
Copyright (c) 1993-2021 by Florian Klaempfl and others
Target OS: Linux for x86-64
Compiling demo_window.pas
Compiling wlgui_app.pas
Compiling wayland_client_core.pas
wayland_client_core.pas(82,15) Warning: An inherited method is hidden by "Dispatch:LongInt;"
Compiling wayland_shared_buffer.pas
wayland_shared_buffer.pas(82,3) Note: Local variable "flags" not used
wayland_client_core.pas(228,3) Note: Local variable "flags" not used
Compiling xdg_shell_protocol.pas
wlgui_app.pas(13,15) Error: Forward type not resolved "TWLWindow"
wlgui_app.pas(69,25) Fatal: There were 1 errors compiling module, stopping
Fatal: Compilation aborted
Error: /usr/bin/ppcx64 returned an error exitcode