Bug 174701 [Viewers] ViewerRow should be reused instead of connected to the Item
Currently we create a ViewerRow ver every Item we create this can degrade performance, we should cache the row and reuse it
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ColumnViewer.java
/*******************************************************************************
 * Copyright (c) 2006 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Tom Schindl <tom.schindl@bestsolution.at> - initial API and implementation; bug 153993
 *												   fix in bug 163317
 *												   fix in bug 151295, bug 167323, bug 167858
 ******************************************************************************/
package org.eclipse.jface.viewers;
import org.eclipse.core.runtime.Assert;
import org.eclipse.swt.events.MouseAdapter;
import org.eclipse.swt.events.MouseEvent;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Item;
import org.eclipse.swt.widgets.Widget;
/**
 * The ColumnViewer is the abstract superclass of viewers that have columns
 * (e.g., AbstractTreeViewer and AbstractTableViewer). Concrete subclasses of
 * {@link ColumnViewer} should implement a matching concrete subclass of
 * {@link ViewerColumn}.
 * 
 * <strong> This class is not intended to be subclassed outside of the JFace
 * viewers framework.</strong>
 *