Bug 59037 [Navigator] Package explorer flicker when switching/closing editors
If 'Link with editor' is active I see a lot of redrawing going on in the Package Explorer view when I switch between editors (or close an open editor). If the file opened in the second editor already appears in the Package Explorer, it is simply selected and there is no flicker. If, however, the view has to be scrolled to show the second file, I see a lot of redrawing before the view is shown in the new position. The Outline view also seems to draw a white background before drawing the content for the active editor, but it's not nearly as annoying as the Package Explorer (it's true that hte PAckage Explorer has much more items, though).
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
* that can contain items.
     *
	 * @throws ArrayIndexOutOfBoundsException if the index is not valid.
     * @since 3.1
	 */
    protected Item getChild (Widget widget, int index) {
		return getChildren(widget)[index];
    }
    /**
     * Returns whether the given SWT item is expanded or collapsed.
     * 
     * @param item
     *           the item
     * @return <code>true</code> if the item is considered expanded and
     *         <code>false</code> if collapsed
     */
    protected abstract boolean getExpanded(Item item);
    /**
     * Returns a list of elements corresponding to expanded nodes in this
     * viewer's tree, including currently hidden ones that are marked as
     * expanded but are under a collapsed ancestor.
     * <p>
     * This method is typically used when preserving the interesting state of a
     * viewer; <code>setExpandedElements</code> is used during the restore.
     * </p>
     * 
     * @return the array of expanded elements
     * @see #setExpandedElements
     */
    public Object[] getExpandedElements() {