after alt-tab, ceases passing input to applications

Status: Beta

Brought to you by: akir, fluxgen

#1046 after alt-tab, ceases passing input to applications

Milestone: v1.3.5

Status: closed-out-of-date

Owner: nobody

Labels: None

Priority: 5

Updated: 2026-03-23

Created: 2012-01-05

Creator: Anonymous

Private: No

Fluxbox 1.3.1 (packaged version, Ubuntu 11.10)
xorg-server 1.10.4

Sometimes after alt-tab, I see the following behaviours:
* keyboard and mouse input no longer passed to applications
* unable to change window focus with mouse (alt-tab will)

I haven't been able to determine particular circumstances which trigger this. Restarting fluxbox will usually make the symptoms go away, but the next alt-tab will often trigger the bug again.

Discussion

Thomas Luebking - 2016-06-28

Sounds like the input or server being grabbed by fluxbox, but isn't reproducible here.
Can you still cause this?

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Mathias Gumz - 2016-07-01

status: open --> closed-out-of-date

Group: --> v1.3.5
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hackerb9 - 2026-02-07

Since this Heisenbug has been tricky to reproduce, I just want to make a note that this bug just bit me with version 1.3.7 (latest version in Debian). I do not know how to debug fluxbox, but I'll add a few new observations in the hope the next time it bites someone, this will be helpful.

Opening a fluxbox CommandDialog and typing NextWindow causes the same problem as Alt-Tab (unable to type in any windows)

Fluxbox is definitely grabbing the keyboard input as xev shows no Key events. (My mouse does work. )

fluxbox-remote Restart allows me to type again in windows until I use alt-tab or run NextWindow from the Command Dialog.

Switching workspaces does not trigger the bug, nor does clicking on a window to select it.

Perhaps this observation will be helpful:

Curiously, fluxbox-remote NextWindow does not cause any problem!

I am able to map Alt-Tab to execute the above command and it works to switch windows without triggering the keyboard blocking bug. (In .fluxbox/keys: Mod1 Tab :exec fluxbox-remote NextWindow).
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Thomas Luebking - 2026-03-22

Any chance to test the git-master code?
1.3.7 is really dated (though there haven't been any releases in years, i think…)

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hackerb9 - 2026-03-23

Where is the git-master? When I click on "CODE" in sourceforge, it only offers CVS and says the project maintainers have to manually switch over to git/svn.

By the way, one of the bug triggers may be the WorkRave program which I have set up to lock the screen to prevent RSI from continuous typing.

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Mathias Gumz - 2026-03-23

https://github.com/fluxbox/fluxbox/

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