IButton hideCapital = new IButton("Hide Capitals");
hideCapital.setLeft(0);
hideCapital.setTop(240);
hideCapital.addClickHandler(new ClickHandler() {
public void onClick(ClickEvent event) {
countryGrid.hideField("capital");
}
});
canvas.addChild(hideCapital);
IButton showCapitals = new IButton("Show Capitals");