XtAppCreateShell() - create top-level widget instance
Widget XtAppCreateShell (String application_name, String application_class,
WidgetClass widget_class, Display *display,
ArgList args, Cardinal num_args)
The XtAppCreateShell(3) function saves the specified application name and application class for qualifying all widget resource specifiers. The application name and application class are used as the left-most components in all widget resource names for this application. XtAppCreateShell(3) should be used to create a new logical application within a program or to create a shell on another display. In the first case, it allows the specification of a new root in the resource hierarchy. In the second case, it uses the resource database associated with the other display.
Note that the widget returned by XtAppCreateShell(3) has the WM_COMMAND property set for session managers (see Chapter 4).
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface