I am using Lubuntu 18.04.

For several times in the past few months, when I am using Firefox to browse webpages or some other applications, clicking ( left, right and middle) by my mouse or touchpad stops working. It is as if there were something else which is invisible, stands between the screen and the Firefox or other application's window, and steals clicks away. I can still move the cursor using my mouse or touchpad, and I can still use my keyboard to type any key and to switch to other application's window (via Alt + Tab).

In that situtation, if I log into another user's session without logging out the current one, the problem doesn't exist in the other user's session. But if I then switch back to the previous session of the original user, the problem remains.

What may cause the problem? It is unlikely the drivers or modules for the mouse or touchpad, since clicking after switching to another user's session still works. Can the cause come from the window manager openbox, lxsession, or something else?

How shall I solve the problem? Any solution resulting in closing the current applications' windows, e.g. restarting Lubuntu or logging out the current session, is the least thing I want to try.


  • 1
    This is too vague. The thing that may stay between the clicks and the apps may be a passive grab -- google for "x11 release all grabs", and see if that fixes it without having to logout/login. – mosvy Aug 3 '19 at 0:20
  • @mosvy Thanks. Do you mean unix.stackexchange.com/a/40472/674? I just ran the two commands there setxkbmap -option grab:break_actions and xdotool key XF86Ungrab, and it doesn't solve the problem. – StackExchange for All Aug 3 '19 at 0:30
  • @mosvy I can still use my keyboard to switch to another application's window and type any key without a problem – StackExchange for All Aug 3 '19 at 0:42
  • @mosvy I ran xdotool key XF86Ungrab for a second time, it seems to solve the problem. Not sure why. – StackExchange for All Aug 3 '19 at 1:10
  • 1
    A way to debug it would be to look which app (if any) is grabbing any mouse button may be with xdotool key XF86LogGrabInfo which will print some info in /var/log/Xorg.$DISPLAY.log (look for grab.*Button). – mosvy Aug 3 '19 at 1:18

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.