for instance, like the code below, I need to change the focus to the Button b from TextField a by press the Tab Key, but it seems not working on this way, and the focus will just go somewhere else on the browser. So, how can I make it work. and also, what is the classes name to set up the Button's view when it get focus.
TextField<String> a = new TextField<String>();
Button b = new Button("B");
a.setTabIndex(0);
b.setTabIndex(1);