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
}
		Widget[] items = internalFindItems(parentElementOrTreePath);
		for (int i = 0; i < items.length; i++) {
			Widget widget = items[i];
			if (widget instanceof Item) {
				Item item = (Item) widget;
				Item[] childItems = getChildren(item);
				if (getExpanded(item)
						|| (childItems.length > 0 && childItems[0].getData() != null)) {
					
					int insertionPosition = position;
					if (insertionPosition == -1) {
						insertionPosition = getItemCount(item);
					}
					createTreeItem(item, element, position);
				}
			} else {
				int insertionPosition = position;
				if (insertionPosition == -1) {
					insertionPosition = getItemCount((Control) widget);
				}
				createTreeItem(widget, element, position);
			}
		}
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.viewers.ColumnViewer#getColumnViewerOwner(int)
	 */