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/ColumnViewerEditor.java
* @param fColumnNumber
	 *            the column number in which the editor is shown
	 */
	protected abstract void setEditor(Control w, Item item, int fColumnNumber);
	/**
	 * set the layout data for the editor
	 * 
	 * @param layoutData
	 *            the layout data used when editor is displayed
	 */
	protected abstract void setLayoutData(CellEditor.LayoutData layoutData);
	/**
	 * @param focusCell updates the cell with the current input focus
	 */
	protected abstract void updateFocusCell(ViewerCell focusCell);
	
	/**
	 * @return the cell currently holding the focus
	 * 
	 */
	public ViewerCell getFocusCell() {
		return null;
	}
	/**
	 * @return the viewer working for
	 */
	protected ColumnViewer getViewer() {
		return viewer;
	}
}