ScreenSaverGracePeriod – how fast can you cross a training room?

We’re faced with an issue where presenters are losing their train of thought mid presentation because their slides are covered up by the screensaver – this would not be a significant problem, except that by the time they get back to wiggle the mouse, the workstation has been locked, and they have to type in their password again.

Clearly, we can’t make presenters use a machine without workstation locking on the screensaver, or these machines would be accessible for hours under potentially “privileged” accounts. [Note that privilege includes social privilege here – if a VP is presenting, even if they’re a restricted user in Windows, any email that comes from them is treated like the word of %deity.]

And I didn’t want them finding their own solution (like the “Brandenberg Concerto” solution, where you simply play the Beethoven clip in Windows Media Player, put it on loop, mute the Media Player, and then minimise it), that might simply disable or prevent the screensaver completely, thus avoiding any chance of lockout.

So we found a really creative solution – ScreenSaverGracePeriod.

This is a registry setting – under HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon – that controls how long you have after a screen saver goes active, to wiggle the mouse and get back to your presentation without encountering the workstation lock. [You’ve probably noticed already that you can wiggle the mouse quickly and not have to re-enter your password.]

It’s only a little unfortunate that the documentation incorrectly describes this as a REG_DWORD setting – our own testing shows that it has to be a REG_SZ, even though the contents are a number, describing the number of seconds ‘grace’ you want. You can use decimal, or hexadecimal if preceded by “0x”.

[Aside – why do Microsoft’s programmers do this? Surely it’s more effort to extract the string and convert it to a number, than have it stored as a number in the first place!]

Note that setting the ScreenSaverGracePeriod to 0 does not disable the workstation lock, it forces it to happen at any point the screensaver goes active, no matter how fast you are. The maximum value is 2,147,483 – seemingly a random number, until you realise that if you express it in thousandths of a second, it’s the largest number that can be expressed in a four byte signed integer.

One thought on “ScreenSaverGracePeriod – how fast can you cross a training room?”

  1. I use the security template that comes with the Microsoft XP hardening guide. It includes additions to group policy such as the screensaver grace period.

    Unfortunately in my environment, the VPs allowed us to enforce a screensaver but only with a ridiculously long timeout so you can go out to lunch without the screen becoming locked. The screensavergraceperiod is moot for us becasue of that.

    Regarding the windows media player issue, don’t forget that for WMP 9 or later you can set User Configuration/Administrative Templates/Windows Components/Windows Media Player/Playback/Allow Screen Saver to allow the screensaver to still run when windows media player is in use.

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