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
Item[] items = getItems(ti);
				for (int i = 0; i < items.length; i++) {
					if (items[i].getData() != null) {
						disassociate(items[i]);
						items[i].dispose();
					} else {
						if (needDummy && !haveDummy) {
							haveDummy = true;
						} else {
							items[i].dispose();
						}
					}
				}
				if (needDummy && !haveDummy) {
					newItem(ti, SWT.NULL, -1);
				}
				return;
			}
		}
		
		
		if (elementChildren == null) {
			if (isTreePathContentProvider() && widget instanceof Item) {
				TreePath path = getTreePathFromItem((Item) widget);
				elementChildren = getSortedChildren(path);
			} else {
				elementChildren = getSortedChildren(parent);
			}
		}
		Control tree = getControl();