To get all benefits of spice protocol, you need to install spice-vdagent into guest operating system.

For most Linux distributions it is already packaged and can be installed using package manager. For windows it should be downloaded from http://www.spice-space.org.

When installing spice-guest-tools you get following functionality:

1. Mouse can enter and leave virtual machine window seamlessly, without need to click to enter or press Ctrl-Alt to leave

2. Clipboard is shared between host and virtual machine

3. You'll get qxl video driver, which improves performance and automatically adjust screen resolution when spice client window is resized.

4. You also get drivers for virtio drivers and serial ports, but they require some manual setup.