Mac OS X provides many ways to control open applications, including these:
You can switch among open applications by clicking the icon of the open application to which you want to switch on the Dock.
You can also move among open applications using the -Tab or Shift--Tab keys. When you press these keys, a list of the currently open applications appears (see Figure 8.9). The active application has a box around it and its name appears under the box. You can move into a different application by pressing the -Tab or Shift--Tab keys until the application you want is selected, or you can click an application to move into it.
Use Exposé to show all open windows and click a window in the application to which you want to switch.
Hide applications quickly by either pressing -H or choosing Application, Hide where Application is the name of the active application.
Quit an open application by holding down the Control key while clicking the application's icon on the Dock. From the pop-up menu, select Quit.
There are several ways to force a hung application to quit. Press Option-Command-Esc to open the Force Quit Applications window, select the application you want to quit, and click Force Quit (see Figure 8.10). (If an application is hung, its name appears in red in the Force Quit Applications window.) Open the Activity Monitor application (Applications/Utilities); select the application (process) you want to quit; and select Process, Quit (or press Option--Q). You can also use the Unix kill command in the Terminal application along with the process number of the application you want to force to quit. Yet another way is to choose the Apple menu and then Force Quit.
When you select the Finder in the Force Quit Applications window, the Force Quit button becomes Relaunch?the Finder must always be running when you are using Mac OS X. If the Finder hangs, force it to relaunch.
To learn more about the Activity Monitor, see "Using the Activity Monitor to Understand and Manage Processes," p. 925.
To learn more about using Unix commands, see Chapter 9, "Unix: Working with the Command Line," p. 243.
You can use the Force Quit Applications window to quickly move into open applications. Just open the window by pressing Option--Esc and then double-click an application shown on the list. That application moves to the front. You can leave the window open all the time if you want to; because it is always on top, it makes a convenient application palette. Of course, if you don't have a lot of screen real estate, this window can get in the way.