Bug 255229 [Viewers] [3.5] NPE in ColumnViewerToolTipSupport
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ColumnViewerToolTipSupport.java
* {@link CellLabelProvider}.
	 *
	 * @param viewer
	 *            the viewer the support is attached to
	 */
	public static void enableFor(ColumnViewer viewer) {
		new ColumnViewerToolTipSupport(viewer, ToolTip.NO_RECREATE, false);
	}
	/**
	 * Enable ToolTip support for the viewer by creating an instance from this
	 * class. To get all necessary informations this support class consults the
	 * {@link CellLabelProvider}.
	 *
	 * @param viewer
	 *            the viewer the support is attached to
	 * @param style
	 *            style passed to control tool tip behavior
	 *
	 * @see ToolTip#RECREATE
	 * @see ToolTip#NO_RECREATE
	 */
	public static void enableFor(ColumnViewer viewer, int style) {
		new ColumnViewerToolTipSupport(viewer, style, false);
	}
	protected Object getToolTipArea(Event event) {
		return viewer.getCell(new Point(event.x, event.y));
	}
	/**
	 * Instead of overwriting this method subclasses should overwrite
	 * {@link #createViewerToolTipContentArea(Event, ViewerCell, Composite)}