User Story

As an app dev, I want to customize the default timeout message window without affecting the default window or messagebox.

Acceptance Criteria

1. the alert message box has its own specific CSS class, so that app devs can customize its appearance with a specific CSS selector.

Details

Currently, its CSS classes are{{z-messagebox-window z-window z-window-modal z-window-shadow}}. If app devs customize it with those selectors, it also affects default window and messagebox.