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IUIAutomationExpandCollapsePattern::Expand Method

  • Article

Displays all child nodes, controls, or content of the UI Automation element.

Syntax

HRESULT Expand(VOID);

Return Value

Returns S_OK if successful, or an error value otherwise.

Remarks

This is a blocking method that returns after the element has been expanded.

There are cases when a element that is marked as a leaf node might not know whether it has children until either the IUIAutomationExpandCollapsePattern::Collapse or the IUIAutomationExpandCollapsePattern::Expand method is called. This behavior is possible with a tree view control that does delayed loading of its child items. For example, Microsoft Windows Explorer might display the expand icon for a node even though there are currently no child items; when the icon is clicked, the control polls for child items, finds none, and removes the expand icon. In these cases clients should listen for a property-changed event on the IUIAutomationExpandCollapsePattern::CurrentExpandCollapseState property.