The ui package These topics cover the built-in classes of the ui class The Interface classThe ui.Interface class provides methods to manipulate the user interface.The Window classThe ui.Window class provides an interface to the window objects created with the OPEN WINDOW instruction.The Form classThe ui.Form class provides an interface to form objects created by an OPEN WINDOW WITH FORM or DISPLAY FORM instruction.The Dialog classThe ui.Dialog class provides a set of methods to configure, query and control the current interactive instruction.The ComboBox classThe ui.ComboBox class provides an interface to the COMBOBOX form field view in the abstract user interface tree.The DragDrop classThe ui.DragDrop class is used to control the events related to drag & drop events.