There is a regression in widgets mode of the screenlocker. To unlock, user has to use mouse to display the password prompt. It should be always shown or appear on keyboard input. Reproducible: Always
*** This bug has been confirmed by popular vote. ***
The screen locker architecture changed with Plasma 5. The classic screen savers are no longer supported. The 4.x series won't see any further feature development, so this feature request won't be implemented as it doesn't apply to our current version any more. I want to thank you for your feature suggestion and I'm sorry that we were not able to provide the requested feature before we retired the affected component.