In recent years, we have witnessed the rapid advent of cloud computing, in which remote software is delivered as a service and accessed by users using a thin client over the Internet. In particular, a traditional desktop application can execute in the remote virtual machines of clouds without re-architecture and provide a personal desktop experience to users through remote display technologies. However, existing cloud desktop applications have isolated environments with virtual machines (VMs), which cannot adequately support application-oriented collaborations between multiple users and VMs. In this paper, we propose a flexible collaboration approach, named CyberLiveApp, to enable live virtual desktop application sharing, based on a cloud and virtualization infrastructure. CyberLiveApp supports secure application sharing and on-demand migration among multiple users or equipment. To support VM desktop sharing among multiple users, we develop a secure access mechanism to distinguish their view privileges, in which window operation events are tracked to compute hidden areas of windows in real time. A proxy-based window filtering mechanism is also proposed to deliver desktops to different users. To achieve the goals of live application sharing and migration between VMs, a presentation redirection approach based on VNC protocol and a VM cloning service based on the Libvirt interface are used. These approaches have been preliminary evaluated on an extended MetaVNC. Results of evaluations have verified that these approaches are effective and useful.