Bug 181061 [Viewers] JFace viewers performance issues in 3.3
A number of the JFace performance tests are red since I20060926-0800.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTableViewer.java
* that a single column of data may be visible in the table. This occurs
	 * when the programmer uses the table like a list, adding items but never
	 * creating a column.
	 * 
	 * @param index
	 *            the index of the column to return
	 * @return the column at the given index
	 * @exception IllegalArgumentException -
	 *                if the index is not between 0 and the number of elements
	 *                in the list minus 1 (inclusive)
	 * 
	 * @since 3.3
	 */
	protected abstract Widget doGetColumn(int index);
	/**
	 * Returns the item at the given, zero-relative index in the receiver.
	 * Throws an exception if the index is out of range.
	 * 
	 * @param index
	 *            the index of the item to return
	 * @return the item at the given index
	 * @exception IllegalArgumentException -
	 *                if the index is not between 0 and the number of elements
	 *                in the list minus 1 (inclusive)
	 * 
	 * @since 3.3
	 */
	protected abstract Item doGetItem(int index);
	/**
	 * Returns an array of {@link Item} that are currently selected in the