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MOUSE(9.4) MOUSE(9.4) NAME mouse - jerq mouse user interface DESCRIPTION Most jerq programs use the mouse for control, either by pointing at things on the screen or by making selections from a menu. The mouse buttons are different from keys on a keyboard in that events are re- ported when a button is released (let `up') as well as depressed (pressed `down'). It therefore matters not only where and when a but- ton is pressed, but for how long. For example, menus are drawn when a button is depressed, and remain displayed as long as the button is held down. While the button is down, moving the cursor over the menu high- lights entries in the menu; the entry (possibly none) under the cursor when the button is released is the selection returned to the program. Large menus also present a `scroll bar' on the left side of the menu. Moving the mouse inside the scroll bar chooses which subset of the available entries are displayed and therefore selectable. There is a convention about how the buttons are used. The left button (button 1) is used to point: selecting which layer to work in, which file inside the editor, some text in the file, etc. The middle button (button 2) produces a menu of actions related to the selection: remove the selected text, replace it, etc. The right button (button 3) presents a menu of global, program-wide actions: pick up a new file, rearrange the files on the screen, etc. Programs follow this conven- tion well enough that an unfamiliar program can often be learned simply by trying it. The main violators of the convention are drawing pro- grams, which use button 1 to draw things and button 2 to undraw them, but this is also a consistent convention. The mouse cursor is usually an arrow pointing at a pixel, but programs often change the cursor to an iconic representation of the program's state. The most common cursors are: arrow standard cursor coffee cup Program will be busy for a while. rectangle and arrow Program expects a rectangle to be `swept out' by pressing a but- ton (usually 3) at one corner and releasing at the diagonally opposite corner. gunsight Program expects an object to be selected by pointing at it and pressing a button (usually 3). upside-down mouse Program is thinking; the mouse is inoperative. MOUSE(9.4)