A window with a layout algorithm that manages child windows. In IBM Open Class, the canvas classes are a set of window classes that enable you to implement dialog boxes. These dialog boxes are used for showing views of objects as both pages in a notebook and as windows that gather information to run an action. The different canvases can manage the size and position of child windows, provide moveable split bars between windows, and support the ability to scroll a window. Canvases include the base class, ICanvas, and its four derived classes: IMultiCellCanvas, ISetCanvas, ISplitCanvas, and IViewport.