Css css = resources.warningPaneCss();
outerElement.addStyleName(css.warningPaneOuter());
outerElement.setVisible(false);
DockPanel innerElement = new DockPanel();
innerElement.addStyleName(css.warningPaneInner());
outerElement.add(innerElement, DockPanel.NORTH);
textElement.addStyleName(css.warningPaneText());
innerElement.add(textElement, DockPanel.CENTER);