Bug 100565 [Viewers] Tree viewer selection not revealed if unchanged
[RC3] Steps: 1. Check out org.eclipse.ui.workbench 2. Open Workbench.java 3. Ctrl-O to open Quick Outline 4. Type "r", note that the field "runEventLoop" is the first match 5. Type "u", note that the field is not shown anymore 6. Type arrow-down key, note that you cannot see the selected entry
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
* parent element. If this viewer does not have a sorter, the elements are
     * added at the end of the parent's list of children in the order given;
     * otherwise, the elements are inserted at the appropriate positions.
     * <p>
     * This method should be called (by the content provider) when elements
     * have been added to the model, in order to cause the viewer to accurately
     * reflect the model. This method only affects the viewer, not the model.
     * </p>
     * 
     * @param parentElement
     *           the parent element
     * @param childElements
     *           the child elements to add
     */
    public void add(Object parentElement, Object[] childElements) {
        Assert.isNotNull(parentElement);
        assertElementsNotNull(childElements);
        Widget widget = findItem(parentElement);
        
        if (widget == null)
            return;
        internalAdd(widget, parentElement, childElements);
    }
	/**
     * Adds the given child elements to this viewer as children of the given
     * parent element.
     * <p>
     * EXPERIMENTAL.  Not to be used except by JDT.
     * This method was added to support JDT's explorations
     * into grouping by working sets, which requires viewers to support multiple