# Tcl/Tk (GUI) extension (optional) - CMake option: FUN_WITH_TCLTK=ON - Purpose: Basic GUI functionality via Tcl/Tk. - Homepage: https://www.tcl.tk/ Opcodes: - OP_TK_EVAL: pops script string; pushes rc (0=OK) - OP_TK_RESULT: pushes last Tcl result string - OP_TK_LOOP: enters main event loop; pushes Nil when done - OP_TK_WM_TITLE: pops title string; sets window title; pushes rc - OP_TK_LABEL: pops text, id; creates/updates label .id; pushes rc - OP_TK_BUTTON: pops text, id; creates/updates button .id; pushes rc - OP_TK_PACK: pops id; packs .id; pushes rc - OP_TK_BIND: pops command, event, id; binds; pushes rc Notes: - Requires Tcl/Tk development headers/libs. - GUI behavior depends on your desktop environment/window manager.