1. GUI ---- Graphical user interface. 2. Controls can exist only within a container . a container is a control that consists of other controls . 3. Windows provides the following types of dialog boxes : Modal --- don’t allow you to switch focus to another area of the application . System modal ---takes controls of the entire Windows environment. It don’s allow the user switch to ,or interact with ,any other Windows application until the System modal dialog box is closed . Modeless --- It stays on the screen and i s available for use at any time . It allows you to switch to another area of the application . 考GUI的同学们可以看看