Bug 163317 [Viewers] Take over SWT programming pattern to JFace Viewers
To open ColumnViewer for reusablility we should not make it final making the constructor protected forces people to subclass it and not directly creating instances from it.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ColumnViewer.java
public void activateCustomTooltips() {
		if (tooltipSupport == null) {
			tooltipSupport = new ToolTipSupport(this);
		} else {
			tooltipSupport.activate();
		}
	}
	/**
	 * Deactivate the support for custom tooltips.
	 */
	public void deactivateCustomTooltips() {
		if (tooltipSupport != null) {
			tooltipSupport.deactivate();
		}
	}
	/**
	 * Update the cached cell object with the given row and column.
	 * 
	 * @param rowItem
	 * @param column
	 * @return ViewerCell
	 */
	 ViewerCell updateCell(ViewerRow rowItem, int column) {
		cell.update(rowItem, column);
		return cell;
	}
	/**
	 * Returns the {@link Item} at the given widget-relative coordinates, or
     * <code>null</code> if there is no item at the given coordinates.
	 *