If you’re working on some confidential document and need to leave your PC for a while, then locking the system is one way to maintain your privacy. Hold down the Windows key, press L, and only someone who knows your user account password will be able to restore access to the computer.

When you’re working on a shared computer which others need to regularly use, though, this may not seem like such a good idea. What you really need is a tool like WinLock, which can password-protect and hide any application window, yet leaves the rest of the computer freely available for everybody who needs it.

Once launched the program runs quietly in the background, consuming a minimal 2.5MB RAM and with only a system tray icon to tell you it’s there.

If you decide you want to protect an application, though, all you have to do is select it, and press Ctrl+Space. The program’s icon moves to your system tray, and that alone may be enough to protect it from casual inspection.

But to actually restore your application you must double-click the icon, and enter the unlock password (“123” by default, although you can change this on WinLock’s launch to whatever you like). At which point the program window reappears and you can carry on as before.

Choose your preferred unlock password and WinLock is ready to go

Does this work? We tried protecting a variety of applications, from the simple to the very complex, and they were all both minimised and restored correctly.

And there’s no immediately obvious way to break this protection. If an attacker manually closes WinLock, for instance, the locked application closes too. Bad news for you (especially if you had unsaved work), but at least your security wasn’t compromised.

But our trials did reveal one significant issue. If you do something on your desktop before you press Ctrl+Space, then the active program is Explorer.exe, and so WinLock will essentially minimise the shell. Which means your taskbar will disappear, along with the system tray, and you’ll have no obvious way to restore it. (You can press Ctrl+Shift+Esc to launch Task Manager, manually close Explorer and restart a new instance, but that’s hardly convenient.)

This isn’t necessarily a fatal problem. WinLock does perform a useful function in allowing you to lock individual applications, and the program provides sufficient security to defeat a casual passer-by.

If you’re going to use the program, though, we’d recommend caution. Be very sure that you select the application you want to protect before pressing the Ctrl+Space hotkey. And it would probably be very wise to save your work beforehand, too, just in case.