Using Active Accessibility to Expose Custom Controls

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Using Active Accessibility to Expose Custom Controls

Description of using active accessibility to expose custom controls for the Tablet PC.

You can use Microsoft® Active Accessibility® as an effective way to make custom controls compatible with accessibility aids.  Active Accessibility requires that the application:

  • Create Component Object Model (COM) objects that represent individual custom controls or groups of controls that properly support the IAccessible interface. (The object may be created on demand when it is requested by an Active Accessibility client.)
  • Call NotifyWinEvent when the controls are created or destroyed, gain or lose focus, or otherwise change state.
  • Handle the WM_GETOBJECT message when used to query properties of the object or objects.

For the purposes of this discussion, a window containing other custom objects also needs to be exposed to Active Accessibility, allowing the client to discover and navigate to the child objects. For more information about how to make custom controls compatible with accessibility aids, see the Accessibility Leave Site section of the MSDN® Library.