Bug 267117 [JFace] Provide possibility for subclasses to check if a column is visible in ViewerRow
Currently this is decided by checking with width but this makes Nebula-Grid fail.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ViewerCell.java
public Control getControl() {
		return row.getControl();
	}
	/**
	 * Get the current index. This can be different from the original index when
	 * columns are reordered
	 * 
	 * @return the current index (as shown in the UI)
	 * @since 3.4
	 */
	public int getVisualIndex() {
		return row.getVisualIndex(getColumnIndex());
	}
	/**
	 * Returns the specified neighbor of this cell, or <code>null</code> if no
	 * neighbor exists in the given direction. Direction constants can be
	 * combined by bitwise OR; for example, this method will return the cell to
	 * the upper-left of the current cell by passing {@link #ABOVE} |
	 * {@link #LEFT}. If <code>sameLevel</code> is <code>true</code>, only cells
	 * in sibling rows (under the same parent) will be considered.
	 * 
	 * @param directionMask
	 *            the direction mask used to identify the requested neighbor
	 *            cell
	 * @param sameLevel
	 *            if <code>true</code>, only consider cells from sibling rows
	 * @return the requested neighbor cell, or <code>null</code> if not found
	 */
	public ViewerCell getNeighbor(int directionMask, boolean sameLevel) {
		ViewerRow row;