Bug 166346 [Viewers] ViewerRow#getCell(Point) not working for Viewers without columns
If the viewer has no rows this should return not null but the ViewerCell at index 0
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ViewerRow.java
*/
	public int getColumnIndex(Point point) {
		int count = getColumnCount();
		for (int i = 0; i < count; i++) {
			if (getBounds(i).contains(point)) {
				return i;
			}
		}
		return -1;
	}
	/**
	 * Get a ViewerCell for the column at index.
	 * 
	 * @param column
	 * @return {@link ViewerCell} or <code>null</code> if the index is
	 *         negative.
	 */
	public ViewerCell getCell(int column) {
		if (column >= 0)
			return new ViewerCell(this, column);
		return null;
	}
	/**
	 * Get the Control for the receiver.
	 * 
	 * @return {@link Control}
	 */
	public abstract Control getControl();
}