Bug 153993 [Viewers] Common Baseclass for Tree/TableEditorImpl
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ColumnViewer.java
private ToolTipSupport tooltipSupport;
	/**
	 * The cell is a cached viewer cell used for refreshing.
	 */
	private ViewerCell cell = new ViewerCell(null, 0);
	/**
	 * Create a new instance of the receiver.
	 */
	public ColumnViewer() {
		super();
	}
	/**
	 * Get the cell at this point.
	 * <p>
	 * <i>Subclasses should overwrite this method and provide a meaningful
	 * implementation</i>
	 * </p>