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 void setBackground(Color background) {
		row.setBackground(columnIndex, background);
	}
	/**
	 * Set the foreground color of the cell.
	 * 
	 * @param foreground
	 */
	public void setForeground(Color foreground) {
		row.setForeground(columnIndex, foreground);
	}
	/**
	 * Set the font of the cell.
	 * 
	 * @param font
	 */
	public void setFont(Font font) {
		row.setFont(columnIndex, font);
	}
	/**
	 * Set the text for the cell.
	 * 
	 * @param text
	 */
	public void setText(String text) {
		row.setText(columnIndex, text);
	}
	/**
	 * Set the Image for the cell.
	 *