XToolKit

XToolKit is the highest level X window interface to facilitate composing GUI (Graphical User Interface) by using GUI components such as buttons, pulldown menus, textWindows, etc., as building blocks. The major differences from the Xlib classes are, the XToolKit invokes user-supplied interaction routines corresponding to the Xevents sent from the Xserver, and provides consistent appearance of those interaction-oriented window parts. Classes consisting the XToolKit has the following inheritance structure.

          xwindow
               panel
                    menubar-panel
                    menu-panel
                    filepanel
                    textviewpanel
                    confirmpanel
               panel-item
                    button-item
                         menu-button-item
                         bitmap-button-item
                    text-item
                    slider-item
                    choice-item
                    joystick-item
               canvas
               textwindow
                    buffertextwindow
                         scrolltextwindow
                    textedit
               scroll-bar
                    horizontal-scroll-bar

Just below the xwindow class are the five basic XToolKit classes: panel, panel-item, canvas, textWindow and scroll-bar. Menubar-panel and menu-panel are defined under the panel. A basic strategy to build a new application window and to make it run upon events is the following:

1. define an application class An application window class should be defined as a subclass of panel that has the capability to lay out XToolKit components.
2. define event handlers In the application class, event handlers that are called upon when buttons are pressed or menu items are selected are defined. An event handler ought to be defined as a method with panel-item specific arguments.
3. define subpanels If you use a menubar-panel, it is placed at the top of the application window, therefore it should be created first by :create-menubar. Similarly menu-panels needs to be defined before the menu-button-items to which menu-panels are associated.
4. create panel-items Panel-items such as button-item, text-item, slider-item, etc., can be created by (send-super :create-item class label object method). Event handlers defined above are connected to each panel-item. These initialization procedures should be defined in the :create method of the application window class. Do not forget to define quit button to make the event dispatcher terminate whenever needed. Any textWindow and canvas can also be placed in the application window via the :locate-item method.
5. create the entire window Sending the :create message to the application class creates the application window with its XToolKit components properly placed in the window.
6. run the event dispatcher In order to receive events from the Xserver and delivers them to the corresponding xwindow, run window-main-loop. On Solaris2, window-main-thread, which delivers events in a different thread, is available. Window-main-thread keeps the toplevel interaction alive. Do not run more than one window-main-thread.