This method is used in a child application (defined by the ui.Interface.setType() method as "child") to specify the name of the MDI container for the child application to use. It accepts a single parameter that should correspond to the name of the MDI container set by the ui.Interface.setName() method in the main MDI application.
Example
Parent app:
MAIN
CALL ui.Interface.setName("main1")
....
END MAIN
Child app:
MAIN
CALL ui.Interface.setContainer("main1")
.....
END MAIN