Bug 24521 [Viewers] TreeViewer.update() does not work correctly with filter
When I add an element which does not satisfy the filtering condition and then update it so that it does, call to update does not show the element. This is because[StructuredViewer.update]: public void update(Object element, String[] properties) { Assert.isNotNull(element); | Widget item = findItem(element); | if (item == null) | return; the code silently ignores that the element may become visible... btw. later in code of this method: if (needsRefilter) { refresh(); return; } This is quite inefficient, as it needs to query all visible items; however only one element may actually change (change visibility and/or sort order).
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/StructuredViewer.java
* @param transferTypes
	 *            the transfer types that are supported by the drop operation
	 * @param listener
	 *            the callback that will be invoked after the drag and drop
	 *            operation finishes
	 * @see org.eclipse.swt.dnd.DND
	 */
	public void addDropSupport(int operations, Transfer[] transferTypes,
			final DropTargetListener listener) {
		Control control = getControl();
		DropTarget dropTarget = new DropTarget(control, operations);
		dropTarget.setTransfer(transferTypes);
		dropTarget.addDropListener(listener);
	}
	/**
	 * Adds the given filter to this viewer, and triggers refiltering and
	 * resorting of the elements. If you want to add more than one filter
	 * consider using {@link StructuredViewer#setFilters(ViewerFilter[])}.
	 * 
	 * @param filter
	 *            a viewer filter
	 * @see StructuredViewer#setFilters(ViewerFilter[])
	 */
	public void addFilter(ViewerFilter filter) {
		if (filters == null) {
			filters = new ArrayList();
		}
		filters.add(filter);
		refresh();
	}