Bug 257919 [Viewers] OwnerDraw: Open type doesn't display the selected type
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/StyledCellLabelProvider.java
/**
	 * Returns the viewer on which this label provider is installed on or <code>null</code> if the
	 * label provider is not installed.
	 * 
	 * @return the viewer on which this label provider is installed on or <code>null</code> if the
	 * label provider is not installed.
	 */
	protected final ColumnViewer getViewer() {
		return this.viewer;
	}
	
	/**
	 * Returns the column on which this label provider is installed on or <code>null</code> if the
	 * label provider is not installed.
	 * 
	 * @return the column on which this label provider is installed on or <code>null</code> if the
	 * label provider is not installed.
	 */
	protected final ViewerColumn getColumn() {
		return this.column;
	}
		
	/* (non-Javadoc)
	 * @see org.eclipse.jface.viewers.OwnerDrawLabelProvider#initialize(org.eclipse.jface.viewers.ColumnViewer, org.eclipse.jface.viewers.ViewerColumn)
	 */
	public void initialize(ColumnViewer viewer, ViewerColumn column) {
		Assert.isTrue(this.viewer == null && this.column == null, "Label provider instance already in use"); 
		
		this.viewer= viewer;