Bug 32254 [Viewers] AbstractTreeViewer uses HashSet to remember expansion state
I20030216 The custom hash table should be used instead. Otherwise expansion state may be lost due to a different equals implementation of the element and the IElementComparer.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/CheckboxTreeViewer.java
}
		return true;
	}
	return false;
}
/**
 * Sets the checked state for the given element and its visible
 * children in this viewer.
 * Assumes that the element has been expanded before. To enforce
 * that the item is expanded, call <code>expandToLevel</code>
 * for the element.
 *
 * @param element the element
 * @param state <code>true</code> if the item should be checked,
 *  and <code>false</code> if it should be unchecked
 * @return <code>true</code> if the checked state could be set, 
 *  and <code>false</code> otherwise
 */
public boolean setSubtreeChecked(Object element, boolean state) {
	Widget widget = internalExpand(element, false);
	if (widget instanceof TreeItem) {
		TreeItem item = (TreeItem) widget;
		item.setChecked(state);
		setCheckedChildren(item, state);
		return true;
	}
	return false;
}
}