1.3. Shell Widgets   

Shell widgets are top-level widgets that provide the necessary interface with the window manager. The Xt Intrinsics provide the following shell classes:

Shell - This is the base class for shell widgets. It is a subclass of
Composite and provides resources for all other types of shells.
Override Shell - used for shell windows that bypass the window manager.
WMShell - contains resources necessary for common window manager protocol.
VendorShell - contains resources used by vendor-specific window managers.
TransientShell - shell windows that can be manipulated by the window manager
but cannot be iconified.
TopLevelShell - used for normal top-level windows.
ApplicationShell - used for an application's top-level window.

A complex Motif application
Fig. 1.9 : A complex Motif application
The Motif toolkit provides the following widgets :

XmDialogShell - used as the parents of modal and modeless Dialogs
associated with other top-level windows.
XmMenuShell - used as the parents of MenuPanes.
VendorShell - provides the common state information and services needed by
the window-manager visible shells.