public void onClick(ClickEvent event) {
registry.clear();
final IMsgOperator operator = registry.getOperator(refWidget, false);
operator.addMsg(msgWarn, null);
nestedContext.setVisible(false);
operator.showMsgs(true);
Window
.alert("No message popup should appear even though showMsgs() was called because the nestedContext's visibliity was just set to false.");
nestedContext.setVisible(true);
operator.showMsgs(true);
Window.alert("Now it should be showing because the nestedContext's visibliity was just set to true.");