Types of Windows

  A primary window is a top-level window that can be
  minimized.  An application's main window is a top-level
  window.

  A secondary window may be attached to another window,
  known as the parent window.  For example, dialog boxes or
  message windows are secondary windows; they are usually
  transient in nature.  A secondary window always moves to the
  top of the screen with its parent window and is displayed on
  top of its parent window.  Secondary windows are minimized
  and restored with their parent windows.

  Additional topics:

  *   Secondary Window Types