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
* 
	 * @param column
	 */
	void setColumn(int column) {
		columnIndex = column;
	}
	/**
	 * Set the row to rowItem and the columnIndex to column.
	 * 
	 * @param rowItem
	 * @param column
	 */
	void update(ViewerRow rowItem, int column, Object element) {
		row = rowItem;
		columnIndex = column;
		this.element = element;
	}
	/**
	 * Return the item for the receiver.
	 * 
	 * @return {@link Item}
	 */
	public Widget getItem() {
		return row.getItem();
	}
	/**
	 * Get the control for this cell.
	 * 
	 * @return {@link Control}
	 */