Today, big surprise: I opened my laptop and was greeted by my desktop grid instead of the usual kscreensaver asking for its password. After a tiny little bit of testing/reproducing, it appears that the screensaver does not launch when a KWin effect is being displayed (tested with grid, present windows from {current desktop,all desktops}) Reproducible: Always Steps to Reproduce: 1. Launch a KWin effect (e.g. Ctrl-F8 for desktop grid) 2. Go to sleep (close your laptop or anything that usually fires up kscreensaver) 3. Wake up Actual Results: Kscreensaver has not been launched, you just have the effect still being displayed Expected Results: Kscreensaver is being displayed (and the KWin effect has been discarded) Version 4.14.0, not available in the drop-down menu.
The real issue is actually not having to enter your password to re-login into your session. This could be a major security flaw, as I expect to see a password prompt as I open my laptop...
Thomas, any idea why kwin effects could block the screen saver kicking in?
Input processing (redirection) -> mouse and kbd are necessarily grabbed. Should affect at least present windows + desktop grid. This cannot really fix on X11. The only way around would be a protocol to have the screenlockers signal "i want the mouse! now!" and all clients reacting to it. (Notice that the problem is not limited to kwin effects: virtually all popups, some sort of autohiding panels, games and whatnot things grab the mouse/keyboard and then locking the screen isn't possible resp. pointless) *** This bug has been marked as a duplicate of bug 234153 ***
> This cannot really fix on X11. to add to this: this bug will automatically be fixed by the switch to Wayland. On Wayland it is impossible for an application to grab keyboard/mouse and thus it's impossible to prevent the screen locker from kicking in.