Abstract: A test system for testing layout services for supporting complex text languages in a graphical user interface (GUI) system. A GUI application is used to test the implementation of locale-specific layout services modules via the Layout Services interface, with little or no modification of the GUI toolkit. The application allows users to modify input and output text layout attributes. The input processing layout is processed and input characters are transformed into presentation layout, and the output data may be analyzed to determine if the correct transformations are being made. The application tool allows users to test a specific locale interface, and returns the result data so that the user may interpret the data. Errors may be detected and isolated to each locale-specific language module.