Bug 157174 [Viewers] Refactor new Viewer API
We are yet not completely happy with the API and refactor it.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/TreeViewer.java
for (int column = 0; column < columnCount; column++) {
			ViewerColumn columnViewer = getViewerColumn(column);
			columnViewer.refresh(updateCell(getRowPartFromItem(treeItem),column));
			
			
			if (item.isDisposed()) {
				unmapElement(element, item);
				return;
			}
		}
	}
	/* (non-Javadoc)
	 * @see org.eclipse.jface.viewers.ColumnViewer#getColumnViewerOwner(int)
	 */
	protected Widget getColumnViewerOwner(int columnIndex) {
		if( columnIndex < 0 || columnIndex > getTree().getColumnCount() ) {
			return null;
		}
		
		if (getTree().getColumnCount() == 0)
			return getTree();
		
		return getTree().getColumn(columnIndex);
	}
	/**
	 * Override to handle tree paths.
	 * 
	 * @see org.eclipse.jface.viewers.StructuredViewer#buildLabel(org.eclipse.jface.viewers.ViewerLabel,
	 *      java.lang.Object)
	 */