Creating visual objects by direct manipulation

Low-cost implementations of graphical user interfaces (GUIs) have relied on the widget library framework. Although conventional widgets are suitable for developing typical GUIs with predetermined interaction styles, application-specific customization of interactions is rather difficult, especially for a non-programmer. Instead, the authors propose a new framework whereby the GUI designers can arbitrarily compose new visual objects recursively from intrinsic primitive objects. The behavior of a composed object is governed by constraints extracted from the trace of operations issued to the graphic editor. A prototype system Oak based on the framework is successfully implemented. Oak allows GUI designers to compose visual objects by direct manipulation allowing non-programmers to create customized widgets of high-degree of complexity