All secondary windows associated with the primary window must also be closed. If the last primary window of an application is closed, the application must also be closed. When an explicit focus policy is in use, any secondary windows holding a TearOff Menu can be removed from the display, except when another window of the application has the focus. Such context-specific dialogs are usually transitory, and the secondary windows can be removed when they are no longer needed. When a secondary window is closed, its parent must not be affected, and any secondary windows that are children of it must also be closed.
Secondary windows are always related to a parent window.
Sometimes the parent is a primary window, sometimes another secondary window. Any window can have any number of secondary window children. Secondary windows are not constrained to be clipped within their parent window, but they must always appear on top of that parent window in the window hierarchy. In a layered window manager, you can think of a primary window and its associated secondary windows as occupying one layer in the window hierarchy. Whenever one window is moved in the hierarchy, all of the associated windows must move accordingly.