In an emulated user interface, the PIGUI's resultant code produces low-level calls and all the look-and-feel compliance is handled by the PIGUI software itself (e.g., for OpenWindows support, the software would NOT produce an XView program that must be compiled with the XView toolkit; the software would produce code that interfaces directly with X intrinsics). To provide an emulated user interface, a package provider has to develop a lot of extra code for look-and-feel support. Emulated user interfaces have the advantage that someone on a X11 workstation, for example, can see how the Macintosh-style UI will look (since the look-and-feel is part of the product). Emulated interfaces have the opportunity to provide a faster GUI than does a layered interface; in addition, it does not require purchase of (or learn how to use) other packages to build GUI software.