ScreenWings is a tiny portable tool which attempts to stop malicious software (or anything else, really) from capturing your screen.
The program is a single executable, under 1MB in size. There's no installation, no drivers or services involved, just run it and you're ready to go.
The interface is equally basic: a small grey dialog with a single icon of a screen (if you have more monitors, you'll get an icon for each one).
To disable screen capture, click the Windows logo so that the screen goes black.
Click the arrow icon in the title bar to minimise the window to the system tray.
Double-click the ScreenWings system tray icon to restore the program.
Click the black screen to enable screen capture again.
In our first tests, ScreenWings worked well. Whatever screen capture route we tried just delivered the same all-black image. Unfortunately this also applied to regular PrtSc and Alt+PrtSc actions, so if you do that a lot you'll have to turn ScreenWings off first, and back on afterwards-- potentially a real hassle.