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/CheckboxTableViewer.java
* Sets to the given value the checked state for all elements in this viewer.
 *
 * @param state <code>true</code> if the element should be checked,
 *  and <code>false</code> if it should be unchecked
 */
public void setAllChecked(boolean state) {
	TableItem[] children = getTable().getItems();
	for (int i = 0; i < children.length; i++) {
		TableItem item = children[i];
		item.setChecked(state);
	}
}
/**
 * Sets to the given value the grayed state for all elements in this viewer.
 *
 * @param state <code>true</code> if the element should be grayed,
 *  and <code>false</code> if it should be ungrayed
 */
public void setAllGrayed(boolean state) {
	TableItem[] children = getTable().getItems();
	for (int i = 0; i < children.length; i++) {
		TableItem item = children[i];
		item.setGrayed(state);
	}
}
/* (non-Javadoc)
 * Method declared on ICheckable.
 */
public boolean setChecked(Object element, boolean state) {
	Assert.isNotNull(element);