I doubt if it's some shortcut.
So a few experiments:
- Does it appear if you boot from the Windows 10 install disc or stick (free to make using the Media Creation Tool).
- Does it appear if you boot into Safe Mode (that's different in Windows 10 from older OS'es)?
- Does it appear in the BIOS setup?
- Does it appear if you boot into Linux (disc or stick, free to make)
And more about your system:
- Do you use the video processing in the CPU (IntelHD or so) or do you use a separate videocard?
- Connected VGA, HDMI or DVI?
- Same on another monitor?
I have a strange box that appeared on my display. i think i hit some keyboard shortcut.
there is a vertical rectangle with sold lines. then a horizontal rectangle with dotted lines.
Where the two intersect, the screen is normal. outside the rectangles, the screen is shaded. i can still see behind it, but it is rather annoying. The screen inside each rectangle (but outside the other) is shaded, but not as dark as completely outside.
i can still click behind it and work as normal. I can't resize or move the rectangles. they also do not show up when i do a screen shot.
it appears to be some kind of a filter.
i have rebooted and tried all the settings i can find. I believe i ht some kind of a key combination which made this appear.

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