I configured my laptop to go to sleep when I close the lid. I also use quite often the Exposé-like effect in KDE to switch windows. When I activate expose and then close the lid, my laptop goes to sleep but the screen is not locked although it should be. When I wake up the laptop, the expose effect is still activated, I can select any window and then continue to work without typing my password.

I use the Plasma lock screen with widgets.

Reproducible: Always

Steps to Reproduce:
1. Configure your laptop to go to sleep when the lid is closed
2. Activate expose
3. Close the lid
4. Open it and wake the laptop
Actual Results:  
The expose effect was still active and I could continue to work without typing my password.

Expected Results:  
The screen should be locked.