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GEOS SDK TechDocs
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5 Input Hierarchies
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5.2 Common Hierarchy Basics
As stated above, GEOS offers three hierarchies you can use for input flow and specification of message destinations. These hierarchies, with their basic purposes, are listed below.
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Focus
The Focus hierarchy designates which object should currently receive keyboard input. Essentially, the focus object has the active keyboard grab. The text objects (VisText and GenText) manage the focus automatically; if you use only these objects for keyboard input, you will not need to understand the focus. The Focus hierarchy is described in full in Using Focus
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Target
The Target hierarchy designates the active view, window, and visible selection which may be acted upon. In most cases, the target will be an object the user has selected and now wishes to alter based on menu and dialog selections. For example, a graphic object selected becomes the target object of the application; when the user selects "Rotate" or some other menu function, the menu sends its message to the selected object via the target hierarchy. The Target hierarchy is described in full in Using Target
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Model
The Model hierarchy designates the model of the data the user can manipulate. This is provided for highly complex applications that need to extend the Target hierarchy for more specific handling of selections. It extends from the GenSystem through the GenApplication and the document control objects. The Model hierarchy is described in full in Using Model
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| GEOS SDK TechDocs
|
| 5 Input Hierarchies
| 5.2 Common Hierarchy Basics