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Programming Interfaces
Input/Output Processes : Handling User Input : Using mouse buttons and events : Portable and physical buttons
Portable and physical buttons
ABL supports four portable mouse buttons:
*SELECT — You can select or choose an object by pointing to it and clicking this mouse button. Any previously selected object becomes deselected.
*EXTEND — You can toggle the selection state of an object by pointing to it and clicking this button. This has no effect on any other object; therefore, you can use the EXTEND button to toggle selection individually on more than one object.
*MENU — If an object has an associated pop-up menu, you can activate that menu by clicking this button.
*MOVE — By pressing and holding this button you can drag an object on the screen.
Although ABL supports four buttons, the standard mouse used with Windows has only two buttons. Therefore, some physical mouse buttons have double functions, or, you must use control keys with one or more buttons. A Windows mouse can also have three physical buttons. The extra button, called the middle button, is not supported by OpenEdge with Windows for triggers on mouse button events. The following table shows the mappings between the ABL portable mouse buttons and the physical mouse buttons in Windows.
Table 39. Mouse buttons in Windows
Portable button
LEFT mouse button
CTRL with LEFT mouse button
RIGHT mouse button
LEFT mouse button
ABL supports two main classes of mouse events—portable and three-button events. You can use portable mouse events to associate triggers with logical actions of any mouse. You can use the three-button mouse events to associate triggers with specific physical actions of a three-button mouse. The names of the portable mouse events come from the mouse key labels listed in the above table (for example, MOUSE–SELECT–CLICK). They also correspond to the names of the portable mouse buttons used to generate them. The names of the three-button mouse events correspond to the physical buttons that generate them on a three-button mouse (for example, LEFT–MOUSE–CLICK). For a complete description of the names and functions of the portable and three-button mouse events, see OpenEdge Development: ABL Reference.
Both portable and three-button mouse events divide into two subclasses—low-level and high-level mouse events. Low-level mouse events are generated by the simplest mouse button actions, while high-level events are generated by more complex actions.