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 setLabelProvider(IBaseLabelProvider labelProvider) {
		Assert.isTrue(labelProvider instanceof ITableLabelProvider
				|| labelProvider instanceof ILabelProvider
				|| labelProvider instanceof CellLabelProvider);
		clearColumnParts();
		super.setLabelProvider(labelProvider);
	}
	/**
	 * Clear the viewer parts for the columns
	 */
	private void clearColumnParts() {
		TreeColumn[] columns = getTree().getColumns();
		if (columns.length == 0)
			getTree().setData(ViewerColumn.COLUMN_VIEWER_KEY, null);
		else {
			for (int i = 0; i < columns.length; i++) {
				columns[i].setData(ViewerColumn.COLUMN_VIEWER_KEY, null);
			}
		}
	}
	/*
	 * (non-Javadoc) Method declared in AbstractTreeViewer.
	 */
	protected void setSelection(List items) {
		Item[] current = getSelection(getTree());
		
		if (isSameSelection(items, current)) {
			return;
		}