Re: Screen Shade/curtain?

Didier Colle

Hi Joseeph,

Thanks for the clarification.

Indeed, showing a blank window would not save energy. But why not simply switching off the screen (power button on an external monitor, or using the Fn+F7 (or similar key combination) on a laptop? Then you have both advantages, the pseudo "privacy" thing, and the energy saving.

I agree with the rest.

If an add-on would be needed, then I believe it is more worth investing in an add-on that can report the status of the screen (backlight level, to what port/screen the video signal is send), a bit like the battery level feature in NVDA (nvda+shift+b)

Kind Regards,


On 17/12/2017 22:04, Joseph Lee wrote:
As noted by some members, screen shade/curtain shows what appears to be a blank screen. This is used to "guarantee" privacy for screen reader users. Note the quotation marks around "guarantee", as it does not really guarantee privacy, as there are means to circumvent this (speech output, braille displays, remote access, etc.).
From what I can gather, this function does not result in extended battery life nor power savings. When this function is turned on, an overlay window is imposed on top of other windows, and turning this off removes this overlay. As I said above, this does not provide privacy as many of you may think.
As for this being part of a screen reader: my overall opinion is that it should not. If people want it, then I think an add-on would be a more appropriate solution. Only after looking at justifications and costs should developers consider adding this into NVDA, in my opinion, and personally for me, a justification that goes along the lines of, "because another screen reader has this" is something I won't even consider.

-----Original Message-----
From: [] On Behalf Of Didier Colle
Sent: Sunday, December 17, 2017 6:37 AM
Subject: Re: [nvda] Screen Shade/curtain?

Hi all,

I am not sure what this functionality is exactly about.

When it is about switching off / dimming the monitor, I do not understand why it would not save on battery....

The backlight of a monitor in a laptop, tablet, smartphone, ... whatever is one of the main power sinks in such systems.

On a laptop, you can often (this may vary between laptops) use Fn+f7 for
switching between different display modes (signal send only to laptop
monitor, signal send to external monitor only or signal send to both) or
Fn+F5 to dim the backlight and Fn+F6 to light it up.When I am on battery
power for a long time, I dim the backlight with Fn+f5 to save battery.

Thus you don't need a NVDA add-on for that, although such add-on may be
useful to read the status of the screen (to which monitor is the signal
send, on what level is the backlight). I have no clue whether windows
has access to such info, let alone it provides an api to request that
info (it might be the case that on some laptops this is a pure BIOS
feature completely transparent to windows).

Once again, I am not sure what this functionality is supposed to be
exactly, and thus I may be speaking about something completely different.

Kind regards,


On 17/12/2017 9:24, Brian's Mail list account via Groups.Io wrote:
From what I know about Windows and indeed most screenreaders, this
function is just for privacy, ie its not going to save any battery.
If that is what you want then I'd have thought it was possible to do
it, kind of like a screensaver that never actually loses focus but
then you need to be able to tell nvda that you want it to use the
invisible window not the visible one.

In the issues tracker there is a thread on this.
Also the ultimate way |of doing this on a desktop is called the
monitor off switch..... ahem.

Sent via blueyonder.
Please address personal email to:-, putting 'Brian Gaff'
in the display name field.
----- Original Message ----- From: "Kevin Chao" <>
To: <>
Sent: Saturday, December 16, 2017 11:30 PM
Subject: [nvda] Screen Shade/curtain?


VoiceOver has had screen curtain feature for a long while and JAWS
got screen shade.

Does NVDA have a similar feature via an add-on or natively?

Join to automatically receive all group messages.