At the bottom of the Interface Builder is a tab layouts, each tab of which contains a number of buttons. These tabs list the classes of CAPI elements that can be used in the design of your interface.
The precise list of items available depends on the package of the current interface. To change this package, choose Interface > Package... and specify a package name in the dialog that appears. You must specify a package which already exists in the Lisp image.
The package of the current interface is not necessarily the same as the current package of the Interface Builder. Like all other tools, the Interface Builder has its own current package, which affects the display of symbol names throughout the tool; see Specifying a package for details. By contrast, the package of the current interface is the package in which the interface is actually defined. The window elements which are available for the current interface depend on the visibility of symbols in that package. By default, both the package of the current interface and the current package of the Interface Builder are set to
An element chosen from any of these areas can be operated on by commands in the Object menu. This menu contains the standard action commands described in Performing operations on selected objects.
LispWorks IDE User Guide (Windows version) - 25 Nov 2011