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
tree.setRedraw(true);
		}
	}
	/**
	 * Updates the "+"/"-" icon of the tree node from the given element. It
	 * calls <code>isExpandable</code> to determine whether an element is
	 * expandable.
	 * 
	 * @param item
	 *            the item
	 * @param element
	 *            the element
	 */
	protected void updatePlus(Item item, Object element) {
		boolean hasPlus = getItemCount(item) > 0;
		boolean needsPlus = isExpandable(item, null, element);
		boolean removeAll = false;
		boolean addDummy = false;
		Object data = item.getData();
		if (data != null && equals(element, data)) {
			
			if (hasPlus != needsPlus) {
				if (needsPlus) {
					addDummy = true;
				} else {
					removeAll = true;
				}
			}
		} else {