Is there a way for TabSheet to display tabs at the bottom

There used to be an addon for this in Vaadin 6, but that doesn't seem to be up to date anymore: https://vaadin.com/directory#!addon/detachedtabs

One way to accomplish this is to write your own "TabSheet" that extends HorizontalLayout and maps buttons to Components that get shown in a layout that you select. In pseudocode:

CssLayout contentLayout = new CssLayout();
TabSelector selector = new TabSelector();
selector.setContentLayout(contentLayout);
selector.addTab("Tab1", component1);
selector.addTab("Tab2", component2); //internally you need to create a button and map it's click to showing the right component in the layout

setContent(new VerticalLayout(contentLayout, selector));

Of course this will still require you to do all styling yourself, but hopefully it'll get you started.