Bug 158778 [Viewers] request for remove(parent, index) API on tree viewer
3.3 It would be helpful to have a 'remove(Object parent, int index)' method on the tree viewer to complement that 'replace(...)' and 'setChildCount(...)' APIs. The debug platform requires such a method to implement filtering in virtual tree views. Rather than performing a 'replace/remove' based on elements, the content provider can make one atomic call to remove an element at a specific index.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/TreeViewer.java
*/
	public void cancelEditing() {
		treeViewerImpl.cancelEditing();
	}
	/*
	 * (non-Javadoc) Method declared in AbstractTreeViewer.
	 */
	protected void doUpdateItem(final Item item, Object element) {
		if (!(item instanceof TreeItem)) {
			return;
		}
		TreeItem treeItem = (TreeItem) item;
		if (treeItem.isDisposed()) {
			unmapElement(element, treeItem);
			return;
		}
		int columnCount = getTree().getColumnCount();
		if (columnCount == 0)
			columnCount = 1;
		for (int column = 0; column < columnCount; column++) {
			ViewerColumn columnViewer = getViewerColumn(column);
			columnViewer.refresh(updateCell(getRowPartFromItem(treeItem),
					column));
			
			
			if (item.isDisposed()) {
				unmapElement(element, item);
				return;
			}
		}