Panel content inside TabSheet not displaying

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The initial draw of the TabSheet the panel and it’s content are painted correctly. However, upon switching tabs the content is not being painted.

public class TestUi extends UI
	@Override protected void init(VaadinRequest request) {

	private void createTabs() {
		TabSheet t = new TabSheet();
		t.addTab(getDummy("Content A"), "A");
		t.addTab(getDummy("Content B"), "B");
		t.addTab(getDummy("Content C"), "C");

	private AbstractComponent getDummy(String txt) {
		Panel panel = new Panel();
		Label c = new Label(txt);
		return panel;

by changing the getDummy method to

	private AbstractComponent getDummy(String txt) {
		return new Label(txt);

Everything works as expected.

What I am seeing, but it appears that at line 123 in Panel the ActionManager is null on subsequent calls to paintContent.

    public void paintContent(PaintTarget target) throws PaintException {
        if (actionManager != null) {
            actionManager.paintActions(null, target);

Maybe it should call getActionManager instead of referencing it directly?