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
*/
	protected void removeAll(Control widget) {
		((Tree) widget).removeAll();
	}
	/**
	 * Sets the cell editors of this tree viewer.
	 * 
	 * @param editors
	 *            the list of cell editors
	 * @since 3.1
	 */
	public void setCellEditors(CellEditor[] editors) {
		treeViewerImpl.setCellEditors(editors);
	}
	/**
	 * Sets the cell modifier of this tree viewer.
	 * 
	 * @param modifier
	 *            the cell modifier
	 * @since 3.1
	 */
	public void setCellModifier(ICellModifier modifier) {
		treeViewerImpl.setCellModifier(modifier);
	}
	/**
	 * Sets the column properties of this tree viewer. The properties must
	 * correspond with the columns of the tree control. They are used to
	 * identify the column in a cell modifier.
	 * 
	 * @param columnProperties