How to reproduce: 1. Have a laptop with external monitor, lock it and wait for screen to go black 2. start typeing your password 3. See first part of password end up on laptopscreen, and the rest on the password-field on the external monitor. 4. if you press enter, it tries to loging in using just a part of your password => fails to login. Expected result: If I start typing my password in one of the password-field, keep focus on that password-field. Additional information: Have 2 external monitor, the one that steels the focus, is my primary screen.
Thanks for your bug reports. Unfortunately it will be difficult to investigate as at least my hardware setup doesn't allow to reproduce. For me the laptop screen and external screen both go black and on again on same time. The real problem seems to me that the screen "goes away" while it should be only in DPMS off mode. This looks like a problem somewhere lower in the stack (X server/driver).
I experience a behavior that I consider counter-intuitive and might be related: When entering the password in a multiscreen setup, the password is only entered on one of the desktops. This is confusing at times, when the focus upon locking was on my secondary screen and upon entering I look at the primary screen where I get no feedback of me typing. I think that the password should be shown on all connected screens instead of having separate input masks.
@max: That sounds good, I can't see any reason to have separate inputs, and it should solve my bug too.
This was fixed in Plasma 5.22.