So the problem never was resolved, but I was able to bypass simply executing "unity --reset"
Then couple of weeks ago that method become useless, but moving to gdm3 was a workaround. Early today I've updated to 18.04 and the problem started to appear on there as well. So I decided to debug a bit and finally was able to find that killing `ibus-ui-gtk3` made the spacebar work normally. For now I've removed such package (ibus-gtk3) as I dont need multiple language entry support -- You received this bug notification because you are a member of compiz packagers, which is subscribed to compiz in Ubuntu. https://bugs.launchpad.net/bugs/664273 Title: Window picker doesn't give back key binding To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/compiz/+bug/664273/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~compiz Post to : compiz@lists.launchpad.net Unsubscribe : https://launchpad.net/~compiz More help : https://help.launchpad.net/ListHelp