private void initEditorToggle() { final RootPanel togglePanel = RootPanel.get("paramsToggleButton"); editorToggle = new ToggleButton(new Image("images/triright.png"), new Image("images/tridown.png")); editorToggle.setDown(false); editorToggle.addStyleName("toggle-button"); togglePanel.add(editorToggle); editorToggle.addClickHandler( new ClickHandler() { @Override public void onClick(final ClickEvent event) { paramsEditor.setEditorExpanded(editorToggle.isDown()); } }); }