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| Allegro CL version 9.0 Unrevised from 8.2 to 9.0. 8.2 version

## on-mouse-in

Arguments: dialog-item

Returns the value of the on-mouse-in event handler for the argument control. The value of the on-mouse-in property should be a function object or a function name (a symbol naming a function). This function is called when the mouse cursor is moved into the control's rectangular area. on-mouse-in may be `nil` if no function need be run.

If an on-mouse-in function is supplied, it should take three arguments, which are (1) the control, (2) the mouse-button-state at the time the mouse moved into the control, and (3) the window that the mouse was most recently in. The return value does not matter.

Many functions take a mouse-button-state argument. This argument is a single integer that tells what combination of mouse buttons and shift keys when the message that is being handled occurred. Each mouse button or shift key is represented by a constant that has a single bit flagged, and so bit tests on the button-state argument can be used to tell whether particular mouse buttons or shift keys were down. The particular constants are `left-mouse-button`, `middle-mouse-button`, `right-mouse-button`, `first-x-button` (see `*ignore-mouse-x-buttons*`), `second-x-button` (see `*ignore-mouse-x-buttons*`), `shift-key`, `control-key`, and `alt-key`.

See also on-mouse-out.

See cg-events.htm for information about event handling in Common Graphics.

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This page was not revised from the 8.2 page.
Created 2012.5.30.

|  | ToC | DocOverview | CGDoc | RelNotes | FAQ | Index | PermutedIndex
| Allegro CL version 9.0 Unrevised from 8.2 to 9.0. 8.2 version