To be useful, a layout manager must be attached to a window.
To attach a layout manager to a window, you use the standard window property LAYOUT-MANAGER. You must do this when you create the window. For example:
DISPLAY STANDARD GRAPHICAL WINDOW, BACKGROUND-LOW, LAYOUT-MANAGER = MY-LAYOUT.
A layout manager records data within itself about the window and controls it is managing. Therefore, you should attach a layout manager to only one window. If you want to use the same layout manager for a second window, you should create a second copy of the layout manager.
Once attached to a window, a layout manager begins operating.