Label extra2 = new Label("Extra2");
grid.addComponents(extra, extra2);
assertSame(grid.getComponent(0, 2), extra);
assertSame(grid.getComponent(1, 2), extra2);
grid.removeAllComponents();
grid.addComponents(extra, extra2);
assertSame(grid.getComponent(0, 0), extra);
assertSame(grid.getComponent(1, 0), extra2);
grid.addComponents(children);