UI Automation Support for the Thumb Control Type

This topic provides information about Microsoft UI Automation support for the Thumb control type.

Thumb controls provide the functionality that enables a control to be moved (or dragged), such as a scroll bar button, or resized, such as a window resizing widget. Note that a thumb control does not provide drag-and-drop functionality. Thumb controls can receive mouse focus but not keyboard focus. The control developer must implement the control so that it acts appropriately (can be dragged or resized).

The following sections define the required UI Automation tree structure, properties, control patterns, and events for the Thumb control type. The UI Automation requirements apply to the Thumb control type, whether Microsoft Windows Presentation Foundation (WPF), Microsoft Win32, or Windows Forms.

This topic contains the following sections.

Required UI Automation Tree Structure

The following table depicts the control view and the content view of the UI Automation tree that pertains to thumb controls and describes what can be contained in each view. For more information about the UI Automation tree, see UI Automation Tree Overview.

Control View Content View
  • Thumb
Not applicable

Thumb controls never appear in the content view because they exist only to be manipulated with a mouse. They are exposed though another control pattern, such as the Scroll pattern, Transform pattern, or RangeValue pattern, being supported on the Thumb container.

Required UI Automation Properties

The following table lists the UI Automation properties whose value or definition is especially relevant to thumb controls. For more information about UI Automation properties, see UI Automation Properties for Clients.

UI Automation Property Value Notes
UIA_AutomationIdPropertyId See notes. The value of this property needs to be unique across all controls in an application.
UIA_BoundingRectanglePropertyId See notes. The outermost rectangle that contains the whole control.
UIA_ClickablePointPropertyId See notes. A point within the visible client area of the thumb control.
UIA_ControlTypePropertyId Thumb This value is the same for all UI frameworks.
UIA_IsContentElementPropertyId FALSE The thumb control is never included in the content view of the UI Automation tree.
UIA_IsControlElementPropertyId TRUE The thumb control is always included in the control view of the UI Automation tree.
UIA_IsKeyboardFocusablePropertyId See notes. If the control can receive keyboard focus, it must support this property. A thumb control can receive the focus if it is used as a "gripper" object for sizing a window or a pane. A thumb control in a slider or scroll bar should never receive the focus.
UIA_LabeledByPropertyId NULL Thumb controls never have a label.
UIA_LocalizedControlTypePropertyId See notes. Localized string corresponding to the Thumb control type. The default value is "thumb" for en-US or English (United States).
UIA_NamePropertyId NULL Because the thumb control is not available in the content view of the UI Automation tree, it does not require a name.

Required UI Automation Control Patterns

The following table lists the UI Automation control patterns required to be supported by thumb controls. For more information on control patterns, see UI Automation Control Patterns Overview.

Control Pattern/Pattern Property Support/Value Notes
ITransformProvider Required Enables the thumb control to be moved on the screen. Because the thumb control typically cannot be resized or rotated, this control pattern primarily supports the Move function.

Required UI Automation Events

The following table lists the UI Automation events that thumb controls are required to support. For more information on events, see UI Automation Events Overview.

UI Automation Event Notes
UIA_AutomationFocusChangedEventId None
UIA_BoundingRectanglePropertyId property-changed event. None
UIA_IsEnabledPropertyId property-changed event. If the control supports the IsEnabled property, it must support this event.
UIA_IsOffscreenPropertyId property-changed event. If the control supports the IsOffscreen property, it must support this event.
UIA_StructureChangedEventId None

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