Bug 127861 [DataBinding] Mark API provisional
examples/org.eclipse.jface.examples.databinding/src/org/eclipse/jface/examples/databinding/contentprovider/test/TreeContentProviderTest.java
set2 = new AsynchronousTestSet();
		set3 = new AsynchronousTestSet();
		
		
		union = new UnionSet();
		union.add(set1);
		union.add(set2);
		union.add(set3);
		
		
		shell = new Shell(Display.getCurrent());
		GridLayout layout = new GridLayout();
		layout.numColumns = 1;
		shell.setLayout(layout);
		
		createTree();
		
		Composite buttonBar = new Composite(shell, SWT.NONE);
		buttonBar.setLayout(new FillLayout(SWT.HORIZONTAL));
		randomize = new Button(buttonBar, SWT.PUSH);
		randomize.setText("Randomize");
		randomize.addSelectionListener(new SelectionAdapter() {
			public void widgetSelected(SelectionEvent e) {
				AsynchronousTestSet.recomputeAll();
				super.widgetSelected(e);
			}
		});
		
		GridData data = new GridData();
		buttonBar.setLayoutData(data);