Why `xev -root -event property` shows duplicate events? It breaks keyboard layout

General Discussion
1

Currently in R4.1 keyboard layout switch is applied and propagated by reacting on XKLAVIER_ALLOW_SECONDARY property being changed in dom0, this changes can be monitored with command:
xev -root -event property

Keyboard layout switch shortcut causes property change of XKLAVIER_ALLOW_SECONDARY appear in the output of this command. That is expected.

But it happens twice! And not in one moment, but sometimes even with time gap up to a second. It breaks keyboard layout switch sometimes, if user switches between active windows at that moment.

Does anybody know why almost all property events a duplicated in this output?

Example of output (I added a couple of new lines for grouping) 
[dom0 ~]$ xev -root -event property

PropertyNotify event, serial 18, synthetic NO, window 0x544,
    atom 0x1ee (XKLAVIER_ALLOW_SECONDARY), time 3435915, state PropertyNewValue

PropertyNotify event, serial 19, synthetic NO, window 0x544,
    atom 0x1ee (XKLAVIER_ALLOW_SECONDARY), time 3435916, state PropertyNewValue

    
PropertyNotify event, serial 19, synthetic NO, window 0x544,
    atom 0x1a3 (_NET_CLIENT_LIST_STACKING), time 3442978, state PropertyNewValue

    
PropertyNotify event, serial 20, synthetic NO, window 0x544,
    atom 0x154 (_NET_ACTIVE_WINDOW), time 3443069, state PropertyNewValue

PropertyNotify event, serial 20, synthetic NO, window 0x544,
    atom 0x154 (_NET_ACTIVE_WINDOW), time 3443069, state PropertyNewValue

    
PropertyNotify event, serial 20, synthetic NO, window 0x544,
    atom 0x1ee (XKLAVIER_ALLOW_SECONDARY), time 3443081, state PropertyNewValue

PropertyNotify event, serial 21, synthetic NO, window 0x544,
    atom 0x1ee (XKLAVIER_ALLOW_SECONDARY), time 3443108, state PropertyNewValue

    
PropertyNotify event, serial 21, synthetic NO, window 0x544,
    atom 0x1a3 (_NET_CLIENT_LIST_STACKING), time 3443542, state PropertyNewValue

    
PropertyNotify event, serial 21, synthetic NO, window 0x544,
    atom 0x154 (_NET_ACTIVE_WINDOW), time 3443550, state PropertyNewValue

PropertyNotify event, serial 21, synthetic NO, window 0x544,
    atom 0x154 (_NET_ACTIVE_WINDOW), time 3443550, state PropertyNewValue

    
PropertyNotify event, serial 24, synthetic NO, window 0x544,
    atom 0x1ee (XKLAVIER_ALLOW_SECONDARY), time 3932489, state PropertyNewValue

PropertyNotify event, serial 24, synthetic NO, window 0x544,
    atom 0x1ee (XKLAVIER_ALLOW_SECONDARY), time 3932491, state PropertyNewValue
2

See also:

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3

Thank you, that is my issue ticket :slight_smile:

I solved this Capslock/Shift+Capslock (and two shortcuts for 2 layouts in general) problem. It is done with a source code hack (and may be broken on updates), but nonetheless now I have much more pleasant experience.

Now I am trying to fix minor layout switch issues of R4.1+, one of them being this one with property events being fired twice for some reason.

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