1. A method for displaying alerts provided by applications of a guest environment in a notification bar controlled by a host operating system (OS) in a host environment of a mobile device, wherein the guest environment is running in a virtual machine supported by a hypervisor running within the host environment, the method comprising: registering, by a hypervisor-aware service running on a guest OS of the virtual machine, with the guest OS to be notified by the guest OS when applications of the guest environment request the guest OS to present alerts in a notification bar controlled by the guest OS, wherein the hypervisor-aware service is aware that it is running in the virtual machine on top of the hypervisor and can request or provide data and services to and from the hypervisor; upon receipt by the hypervisor-aware service of a notification by the guest OS of an application requesting presentation of an alert in the notification bar controlled by the guest OS, forwarding the notification to the hypervisor, wherein the alert is one of an e-mail alert, a calendar alert, and a telephone call alert; and transmitting, by the hypervisor, a corresponding request to a notification management component of the host OS to present the alert on the notification bar controlled by the host OS, the notification management component configured to present the alert on the notification bar controlled by the host OS concurrently with a notification from an application of the host OS and system information generated by the host OS; wherein display of the notification bar controlled by the host OS persists when a user interface (UI) of the guest environment is displayed in place of a UI of the host environment and when the UI of the host environment is displayed in place of the UI of the guest environment, and wherein, upon a swipe motion by a user on the notification bar controlled by the host OS, the host OS displays an expanded notification bar that comprises additional detailed information that differentiates alerts of applications of the guest OS from alerts of applications of the host OS.