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 item = items[i];
			Widget o = internalFindItem(item, element);
			if (o != null) {
				return o;
			}
		}
		return null;
	}
	
	protected void internalRefresh(Object element) {
		internalRefresh(element, true);
	}
	
	protected void internalRefresh(Object element, boolean updateLabels) {
		
		if (element == null) {
			internalRefresh(getControl(), getRoot(), true, updateLabels);
			return;
		}
		Widget[] items = findItems(element);
		if (items.length != 0) {
			for (int i = 0; i < items.length; i++) {
				
				internalRefresh(items[i], element, true, updateLabels);
			}
		}
	}
	/**
	 * Refreshes the tree starting at the given widget.
	 * <p>