Bug 258736 [Viewers] [JFace] setUseHashLookUp() and multiple occurrences of same domain object in TreeViewer
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/TreeViewer.java
public Control getControl() {
		return tree;
	}
	/*
	 * (non-Javadoc) Method declared in AbstractTreeViewer.
	 */
	protected boolean getExpanded(Item item) {
		return ((TreeItem) item).getExpanded();
	}
	/*
	 * (non-Javadoc)
	 *
	 * @see org.eclipse.jface.viewers.ColumnViewer#getItemAt(org.eclipse.swt.graphics.Point)
	 */
	protected Item getItemAt(Point p) {
		TreeItem[] selection = tree.getSelection();
		if( selection.length == 1 ) {
			int columnCount = tree.getColumnCount();
			for( int i = 0; i < columnCount; i++ ) {
				if( selection[0].getBounds(i).contains(p) ) {
					return selection[0];
				}
			}
		}
		return getTree().getItem(p);
	}
	/*
	 * (non-Javadoc) Method declared in AbstractTreeViewer.
	 */
	protected int getItemCount(Control widget) {