<hardware> To press and release a button on a mouse or other pointing
device. This generates an event, also specifying the screen position, which is
processed by the window manager or application program.
On a mouse with more than one button, the unqualified term usually implies
pressing the left-most button (with the right index finger), other buttons would
be qualified, e.g. "right-click". Multiple clicks in quick succession, e.g. a
double-click, often have a different meaning from slow single clicks. Keyboard
modifiers may also be used, e.g. "shift-click", meaning to hold down the shift
key on the keyboard while clicking the mouse button.
If the mouse moves while the button is pressed then this is a drag.
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