Windows screen saver appears when watching video inside VM

[HaroldFinch]

Host = Win 7 Pro 64 bit
VirtualBox = 4.3.24 r98716
Guest = Xubuntu 14.10

When I watch web site videos from inside my VM (Xubuntu guest OS), if I do not move my mouse for several seconds, eventually the host OS (Windows) screen saver kicks in and swamps the screen with its stuff. This happens regardless of whether or not the VM is in full screen mode. The only cure that I know of is to move to mouse to break out of the Windows screen saver, but that is obviously quite annoying when watching a video.

In contrast, when I watch a web video when fully inside the Windows host, something communicates to the OS that the video is sufficient activity to prevent the screen saver from kicking in.

Is there any configuration that can be done to have a guest OS signal to a host Windows OS that the Windows screen saver should not kick in?

[scottgus1]

Imagine that you have two physical PCs instead, Xubuntu and Windows, with a keyboard/mouse switch. You watch a video on the Xubuntu PC successfully. The WIndows PC turns on its screensaver in the meantime. How would you get the Windows machine not to trigger the screensaver when you're watching things on the Xubuntu?

This is essentially the situation you have with your setup. Two OS's on two PC's, albeit one existing within the other. Unless I haven't noticed something that Virtualbox has (certainly possible), I don't believe Virtualbox has a way to let the host OS know there's a video playing in the guest, so don't trigger the host screensaver. You'll have to either remember to disable the host OS's screensaver, or come up with a script that runs in your guest, monitors whatever the guest OS uses to avoid running screensavers when a video is being played, and communicate with a concurrent script in the host to disable the host screensaver (No idea how to do that myself.)

[loukingjr]

You could create a HotKey for Windows that toggles the screen saver on and off.

[HaroldFinch]

Imagine that you have two physical PCs instead, Xubuntu and Windows, with a keyboard/mouse switch. You watch a video on the Xubuntu PC successfully. The WIndows PC turns on its screensaver in the meantime. How would you get the Windows machine not to trigger the screensaver when you're watching things on the Xubuntu?

One possibility would be the VirtualBox Guest Additions. They allow all sorts of guest/host communication. So in theory, it seems to me that it could include communication from the guest OS that is playing a video.

From the manual, consider this select quote:

Generic host/guest communication channels

The Guest Additions enable you to control and monitor guest execution in ways other than those mentioned above. The so-called "guest properties" provide a generic string-based mechanism to exchange data bits between a guest and a host, some of which have special meanings for controlling and monitoring the guest;

In my case, I am proposing that the host should be able to communicate back to the host. In particular, the host Windows VirtualBox process should be able to read info from the guest and make Windows calls that suppress the screen saver.

[scottgus1]

You're quite right, Harold, the guestproperty system does allow communication between guest & host. I use that system myself to monitor the "heartbeat" and transmit "fully booted status" of my essential guests. One could make a guestproperty called PlayingVideo, and toggle it true and false to tell when a video is being played and whether to allow the host screensaver. The "Can I toggle the guestproperty and read it" part does exist in Virtualbox. The "Am I playing a video" part and the "Do I turn off the screensaver" part don't exist in Virtualbox. You can ask the developers to put those parts in, on the Bugtracker, see www.virtualbox.org, Community section. Call your suggestion out as an Enhancement, see what they say.
Meanwhile, and if the devs say no, thereafter, you'll need scripts running in the host and guest to monitor your guestproperty, and make the appropriate changes when necessary.