Bug 172019 [Viewers] Plus sign doesn't disappear when using deferred content providers
3.3 M4 Use a tree viewer with a content provider using IDeferredWorkbenchAdapter and DeferredTreeContentManager. When fetchDeferredChildren is call and no elements are reported to the element collector the plus sign of the node doesn't disappear. This work without problems under Windows and Mac/OS (e.g. the plus sign disappears).
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
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) {
		createChildren(event.item);
		if (event.item.getData() != null) {
			fireTreeExpanded(new TreeExpansionEvent(this, event.item.getData()));
		}
	}
	
	protected void hookControl(Control control) {
		super.hookControl(control);
		addTreeListener(control, new TreeListener() {
			public void treeExpanded(TreeEvent event) {
				handleTreeExpand(event);
			}
			public void treeCollapsed(TreeEvent event) {
				handleTreeCollapse(event);
			}
		});
	}
	/*
	 * (non-Javadoc) Method declared on StructuredViewer. Builds the initial