2.3 Managing windows

Unfortunately, the management of windows on a workstation screen depends heavily on the type of window manager and on the setup files defined for your login. At best, we can only be approximate here and try to describe general characteristics of normal setups.

2.3.1 General window management

Most window managers allow multiple windows to be created on the screen at the same time. These windows can either be closed in a small “iconified” form or opened in a larger and more usable form. Windows are normally opened by positioning the cursor on the icon with the mouse and clicking either once or twice with the left button. You can type only into open windows. An open window can be resized usually by “grabbing” (position the cursor with the mouse and then hold down the mouse button) one of its corners with the left mouse button. Windows under twm have a widget in the upper right corner which must be grabbed with any of the buttons. Positioning the cursor in the top bar of a window border and holding down a mouse button will do something. Usually, the left button moves the window, the middle button puts the window above or below other windows, and the right button gets you a pull-down menu of all the window manipulation options. Under Motif the middle and right buttons are switched. In the upper left corner of the top bar is a special button widget. Under Openlook and twm, clicking on this widget iconifies the window. Under Motif the iconify widget is shown as a dot and is usually in the upper right corner. The widget in the upper left corner under Motif offers a pull-down menu of window options, but is dangerous since a double click on that widget with the left button destroys the window (and any programs running in it).

Positioning the cursor in the root window (the background) and holding down a mouse button usually gets a pull-down menu with programs that can be run and various other options including exiting from the system. Well-configured systems offer a separate menu with each button. This is usually the way to get more windows if you need them.

When encountering a system for the first time, you should explore what the various controls have to offer. Position in the background, press each button in turn, and follow up what is offered by the pull-down menus which appear. Many menu items may themselves have a menu which you get by dragging the cursor to the right. Usually there is an arrow at the right of the menu item to indicate this. Then, try to open some icons with a single click or a quick double click. Then try the various mouse buttons in the top bar, the corners, and any special widgets visible in the window. Some windows also have scroll bars along the left or right side. Experiment with the various mouse buttons, clicking or dragging, in the scroll-bar region to see how to scroll back to previous text or forward to the last line. It pays to master all this slight of hand to allow you rapid access to multiple windows, previous text, and the like. It is very painful to click the wrong button and destroy a program that has been running for a few hours already!

2.3.2 Managing the AIPS TV window called XAS

On workstations, AIPS simulates a real TV display with a program called XAS. The program starts when you start AIPS and comes up in an open form. Its icon shows a cute drawing of an ape along with words like AIPSTV UNIX for local display and AIPSTV INET for Internet-connectivity. In many ways, this is a normal window which can be resized, moved, iconified, and destroyed like any other. However, when the window is open and the cursor positioned inside the window, XAS offers some additional features. The cursor changes shape and color in the window to indicate this fact. To get XAS to treat the cursor position as a “TV cursor” position, you must hold down the left mouse button. This allows the cursor to fill two rôles at nearly the same time, that of a workstation cursor and of a TV cursor. You do not have to hold the button down for long to register a TV position and, in fact, it is more efficient in interactive TV operations simply to click the left button at the desired locations. When you drag the cursor, numerous intermediate values are read with consequent extra computation. Note that the TV cursor position is read by XAS whenever the cursor is in the XAS window with the left button down. However, that position is only used when some verb or task reads it from XAS and uses it for some purpose, e.g., to select image coordinates or to control image enhancement.

AIPS TV functions refer to “buttons” A, B, C, and D for the purpose of signaling conditions to the software. In the XAS simulation, these buttons are the keys a, A, or F3 for button A, keys b, B, or F4 for button B, keys c, C, or F5 for button C, and keys d, D, or F6 for button D. The F2 and F7 buttons toggle the size of the display from full screen to whatever size you set the window. XAS simulates a TV with a number, usually sixteen, of grey-scale memories and eight one-bit graphics overlays. The x and y dimensions of the memories adapt to the display area of your workstation less some room for window borders and, sometimes, for a few lines of a type-in window as well. XAS has the ability to display full-color (256 levels for each of red, green, and blue) on terminals capable of supporting full “TrueColor visuals.” The internal dynamic range of images in XAS is actually 0:8191, but displays are limited to 0:255. You pay for this capability with a small reduction in speed for ordinary enhancements, blinks, and the like. You may select to limit your XAS to a “PseudoColor visual” which is all that is available on some older workstations. In that mode, the higher the number of grey levels the greater the dynamic range is available in the display of images. The maximum allowed maximum grey level is 235, but this will use all 256 levels of a “colormap” and therefore force XAS to use its own colormap. When the cursor enters the XAS window, the computer switches to that special colormap changing all of the other colors in the other windows (often in ways that are very undesirable). The default number of grey levels is 199 which may be small enough to avoid this effect or to manage to leave the colors of your most basic windows unaffected. Type HELP XAS  C R when in AIPS to see how to control the number of levels, the colors of the graphics overlay planes, and numerous other parameters.