Bug 154064 Need a way to access the TreeItem or TableItem on a refresh
It is not currently possible to know when an item is refreshed. This is required for ownerDraw support in viewers.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ViewerCell.java
public ViewerCell(ViewerRow row, int columnIndex) {
		this.row = row;
		this.columnIndex = columnIndex;
	}
	
	/**
	 * Get the index of the cell.
	 * @return int
	 */
	public int getColumnIndex() {
		return columnIndex;
	}
	
	/**
	 * Get the bounds of the cell.
	 * @return Rectangle
	 */
	public Rectangle getBounds() {
		return row.getBounds(columnIndex);
	}
	
	/**
	 * Get the element this row represents.
	 * @return Object
	 */
	public Object getElement() {
		return row.getItem().getData();
	}
}