... BSD-basedUNIX to System V Release 4–basedUNIX, from OpenWindows to Motif, from PC to UNIX to Macintosh (or some combination thereof), andbetween various other alternatives, too numerous to mention. ... chapter.1.1.3.2 The Button classA button is little more than a label that you can click on. Selecting a button trig-gers an event telling the program to go to work. Section 5.3 explores theButtoncomponent. ... passes it along to a handler to process the event.If nobody wants to handle the event, the system ignores it. Unlike some windowingenvironments, you do not have to provide a main loop to catch and...