Bug 164989 [Viewers] ColumnViewer#getColumnViewerOwner() doesn't respects column count
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ColumnViewer.java
*            in
	 * @return ViewerRow the row or <code>null</code>if no row is found at
	 *         this point
	 */
	protected ViewerRow getViewerRow(Point point) {
		Item item = getItemAt(point);
		if (item != null) {
			return getViewerRowFromItem(item);
		}
		return null;
	}
	/**
	 * Get the ViewerRow associated with the Widget.
	 * 
	 * @param item
	 * @return ViewerRow
	 */
	protected ViewerRow getViewerRowFromItem(Widget item) {
		return (ViewerRow) item.getData(ViewerRow.ROWPART_KEY);
	}
	/**
	 * Get the widget for the column at columnIndex.
	 * 
	 * @param columnIndex
	 * @return Widget
	 */
	protected abstract Widget getColumnViewerOwner(int columnIndex);
	/**
	 * Returns the cell modifier of this viewer.
	 *