version 13/130803 by Jon Ingold
Chapter: Constructing a Layout
All games start, by default, with a status bar along the top of the screen, and the main window below. Glulx windows are formed from the main window by carving off segments using either horizontal or vertical strokes, with each stroke creating one new window, from which further windows can be cut. This automatically creates a tree-structure for windows, with each new window being sliced from one that came before. The extension refers to this process as "spawning", and you set up your layout of windows by telling the game which window spawns which.
These relationships - which window spawns which - must be inflexible throughout the game: although they may be multiple structures which the game can chop and change between, altering which window spawns which will likely cause UNDO and RESTORE commands to fail in strange ways. However, in practice this isn't too much of a restriction, as two windows with different names can easily be made to do the same things (see the section on Using the Windows, below).
One g-window object is created by default, though its properties are unimportant. It is called main-window, and its purpose is to spawn other windows.