Presentation Manager applications revolve around the concept of windows. A window appears as a rectangular area on the screen, in which information may be displayed and user input entered.
An application may create multiple windows, and multiple windows created by one or more applications may be displayed concurrently on the screen.
While the Presentation Manager interface is graphics-oriented, the information input and output through a window need not be graphical; text may be manipulated in windows without the complication of using graphics fonts. While a mouse is recommended for user interaction in the Presentation Manager environment, many Presentation Manager functions can be achieved by the use of the keyboard only.
Windows are displayed on the screen overlaying a background known as the desktop. This desktop may be altered to any color, or a bitmapped image may be displayed, using utilities provided with Presentation Manager as part of OS/2 Version 2.0.
An application may create multiple windows; the desktop may simultaneously display multiple windows created by multiple applications, and these windows may be updated concurrently by their parent applications, due to the multitasking nature of the OS/2 operating system. However, since OS/2 is a single-user system, the user provides input to only one window at a time. This window is said to possess the input focus. The user may switch the input focus from one window to another by pointing to the desired window with the mouse and pressing mouse button 1, or with the keyboard using the Ctrl+Esc or Alt+Esc key combinations.
The use of the mouse button depends on whether the user is left- or right-handed. It can be selected during the installation process of OS/2 Version 2.0. In this document we conform to the CUA convention of using mouse button 1 (MB1) for "select" and mouse button 2 (MB2) for "drag" functions. More information on this is provided in WPS Navigation and Techniques.
When many windows are displayed on the desktop at one time, the desktop can become cluttered and almost unworkable. To avoid this situation and remove unwanted windows from the screen without terminating their associated applications, Presentation Manager allows the user to minimize a window. When a window is minimized, it is removed from the desktop and its icon is placed in the Minimized Window Viewer folder. See Icons for a further discussion of this.
Clicking MB2 on an icon causes Presentation Manager to display a context (or pop-up) menu. This lets the user restore, move or close the window (that is, terminate the application). If the user "double clicks" MB1 on the icon, Presentation Manager will restore the window to its previous size and position on the screen, without displaying the menu.
In order to display a window to the full size of the display screen, a user may maximize a window. The window is then resized to the maximum defined by the program. For some programs this will be the whole screen. A window may also be restored to its former size and position on the screen. See Frame Area for a description of the way in which this is achieved.
A window on the screen consists of two distinct areas; the frame area and the client area. The frame area allows the user to manipulate the window (that is, resize the window, move the window on the screen, etc.) while the client area is used by the application to display information and solicit user input.