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
updateSelection(selection);
			}
			fireDoubleClick(new DoubleClickEvent(this, selection));
		}
	}
	/**
	 * Handles a tree collapse event from the SWT widget.
	 * 
	 * @param event
	 *            the SWT tree event
	 */
	protected void handleTreeCollapse(TreeEvent event) {
		if (event.item.getData() != null) {
			fireTreeCollapsed(new TreeExpansionEvent(this, event.item.getData()));
		}
	}
	/**
	 * Handles a tree expand event from the SWT widget.
	 * 
	 * @param event
	 *            the SWT tree event
	 */
	protected void handleTreeExpand(TreeEvent event) {
		if (!(getContentProvider() instanceof ILazyTreeContentProvider)) {
			createChildren(event.item);
		}
		if (event.item.getData() != null) {
			fireTreeExpanded(new TreeExpansionEvent(this, event.item.getData()));
		}
	}