Daanav Screen

Surely enough you hit Win + L to lock your desktop whenever you leave the computer, even if it’s for a short while. This isn’t of any use if your account is not protected by a password. There are, however, third-party applications like Daanav Screen which can protect your desktop even without a password.

A transparent protection screen

First of all, you need to be sure that Microsoft Visual C++ Redistributable Package is installed on your computer for the application to successfully function. There’s no actual interface to the application, but this doesn’t make it difficult to use. A prompt shows up on launch, letting you know how things work.
What the application does is cover your desktop with a completely transparent veil which prevents interaction with anything. This means that clicking or using the keyboard has no effect, which is a neat security trick, leaving individuals to think your computer is frozen. Just be sure that nobody attempts to play the hero and forcefully restarts the PC, which can lead to loss of data.

Good, but far from being a pro

The only way to tell whether or not the application is active is through the lack of interaction with screen elements. Deactivating it requires incredibly little effort, namely to hit the Escape key. Unfortunately, there’s no possibility to set a different key, or even a combination, which kind of leaves your computer vulnerable.
Just so you don’t look for the executable every time you want to lock the PC, a cool trick is to assign a hotkey command to its shortcut from the Properties panel, which allows you to launch it regardless of location.
Security isn’t maximum, though, because there are still workarounds to bypass the transparent veil. For instance, the task switcher temporarily makes a window in the background usable, but the veil switches back after a short while. Even the Task Manager can be brought up through the Ctrl + Shift + Esc key, unveiling the process which can be terminated.

In conclusion

To sum it up, Daanav Screen isn’t really the application you’re looking for to enhance security while away. There’s no option to make it automatically kick in when your PC is idle, while the lack of options to change the exit key leaves your computer pretty vulnerable.