When mouse is on task bar application that is started but not on the front, KDE shows task bar thumbnail and moves this app to the front and makes it transparent. If press keyboard short cut for screen lock at this time, workstation becomes locked, but screen doesn't change. I mean all windows stays as they was when you press lock short cut, but you can't interact with it. It' confusing

Reproducible: Always

Steps to Reproduce:
1.Make sure that "taskbar thumbnails" and "highlight window" effects are active
2.Set keyboard short cut for lock screen action. I use control + shift + eject(apple keyboard)
3.Open several application
4.Hover over task bar to the other started application
5.Make sure, that thumbnails is shown and windows become transparent
6.Press lock short cut on keyboard
Actual Results:  
Workstation becomes locked, but screen doesn't change, mouse is active, but there's no window with password prompt

Expected Results:  
Workstation becomes locked, screen changes to the standard lock screen with background image and password prompt window.

In this situation you can unlock your workstation if you enter your password, but if you have several keyboard layouts, or prompt loses focus, this problem becomes very difficult to solve.


KDE Platform Version 4.12.2
Linux 3.12.9-2-ARCH #1 SMP PREEMPT x86_64