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/AbstractTreeViewer.java
}
	private void internalCollectVisibleExpanded(ArrayList result, Widget widget) {
		Item[] items = getChildren(widget);
		for (int i = 0; i < items.length; i++) {
			Item item = items[i];
			if (getExpanded(item)) {
				Object data = item.getData();
				if (data != null) {
					result.add(data);
				}
				
				
				internalCollectVisibleExpanded(result, item);
			}
		}
	}
	/**
	 * Returns the tree path for the given item.
	 * 
	 * @since 3.2
	 */
	protected TreePath getTreePathFromItem(Item item) {
		LinkedList segments = new LinkedList();
		while (item != null) {
			Object segment = item.getData();
			Assert.isNotNull(segment);
			segments.addFirst(segment);
			item = getParentItem(item);
		}
		return new TreePath(segments.toArray());