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
if (isExpandable(parentItem.getData())) {
                    newItem(parentItem, SWT.NULL, -1);
                } else {
                    
                    tree.redraw();
                }
            }
        }
    }
    /**
     * Sets the expanded state of all items to correspond to the given set of
     * expanded elements.
     * 
     * @param expandedElements
     *           the set (element type: <code>Object</code>) of elements
     *           which are expanded
     * @param widget
     *           the widget
     */
    private void internalSetExpanded(CustomHashtable expandedElements,
            Widget widget) {
        Item[] items = getChildren(widget);
        for (int i = 0; i < items.length; i++) {
            Item item = items[i];
            Object data = item.getData();
            if (data != null) {
                
                
                boolean expanded = expandedElements.remove(data) != null;
                if (expanded != getExpanded(item)) {