A lot of definitions are using Multi_key since version first commit of that file. Which change in particular caused you that trouble? What is the switching option you're using?

Sorry! Now i see what Multi_key was there for ages. 

For many years, i have entered cyrillic letters with pressed LWIN, while capital cyrillic letters was entered with LWIN+LFSH without problem. Problems begun from update to 1.4.0.90 on my box. Now i don't know if this is related to switch to the evdev driver or some xkeyboard-config change. But also i have found a workaround which have caused me to write this bug. If in the file symbols/group change definition:

partial modifier_keys
xkb_symbols "lwin_switch" {
  key <LWIN> {
    symbols[Group1] = [ Mode_switch, Multi_key ],
    virtualMods= AltGr
    };
};

to the form “symbols[Group1] = [ Mode_switch ],” (without Multikey), then my new problems completely gone. 

My current layout and options is set by this command (since update to xorg 1.4.0.90):

setxkbmap -model evdev -rules xorg -layout en_US,ru -variant ,winkeys -option -option grp:caps_toggle,grp:lwin_switch,grp_led:scroll,compose:menu,lv3:ralt_switch,keypad:oss,numpad:microsoft

Old configuration was in the file /etc/X11/xorg.conf and look like this:

    Driver         "kbd"
    Option         "AutoRepeat" "500 30"
    Option         "XkbRules" "xorg"
    Option         "XkbModel" "pc105"
    Option         "XkbLayout" "en_US,ru(winkeys)"
    Option         "XkbOptions" "grp:caps_toggle,grp:lwin_switch,grp_led:scroll,compose:menu,lv3:ralt_switch,keypad:oss,numpad:microsoft"

Because now i'm not sure if my problems directly related to the xkeyboard-config, please feel free to close this bug. Sorry again.

Since the problem is here, and no changes on xkeyboard-config side, I am moving this bug to the keyboard driver. I SUSPECT it is about evdev driver. Would you consider changing the driver temporarily to good old kbd and checking the behaviour?

(In reply to comment #2)
> For many years, i have entered cyrillic letters with pressed LWIN, while
> capital cyrillic letters was entered with LWIN+LFSH without problem. Problems
> begun from update to 1.4.0.90 on my box. Now i don't know if this is related to
> switch to the evdev driver or some xkeyboard-config change. But also i have
> found a workaround which have caused me to write this bug. If in the file
> symbols/group change definition:

Did it happen with 1.4.0? If not, can you please git-bisect it?

@Sergey V. Udaltsov
Thank you!

> Would you consider changing the driver temporarily to good old kbd and checking the behaviour?

I have folowed this steps:

1. To use /etc/X11/xorg.conf input configuration, i have added “Option "AutoAddDevices" "false"”

2. My kbd configuration looks like:

   Driver         "kbd"
   Option         "AutoRepeat" "500 30"
   Option         "XkbRules" "xorg"
   Option         "XkbModel" "pc105"
   Option         "XkbLayout" "en_US,ru(winkeys)"
   Option         "XkbOptions" "grp:caps_toggle,grp:lwin_switch,grp_led:scroll,compose:menu,lv3:ralt_switch,keypad:oss,numpad:microsoft"

Result: no problems.

3. Evdev variant looks like:

   Driver         "evdev"
   Option    "Device" "/dev/input/event0"
   Option         "AutoRepeat" "500 30"
   Option         "XkbRules" "xorg"
   Option         "XkbModel" "evdev"
   Option         "XkbLayout" "en_US,ru(winkeys)"
   Option         "XkbOptions" "grp:caps_toggle,grp:lwin_switch,grp_led:scroll,compose:menu,lv3:ralt_switch,keypad:oss,numpad:microsoft"

Result: problem exists.

Please look at attachments for differences between kbd and evdev in a sence of xev output. In both sessions i have pressed <LWIN>, than <LFSH>, than <J>, than release everything and press Alt+F4 to close xev window. Please note autorepeat of Mode_switch/Multi_key in evdev variant not seen in kbd variant — that cause a size differences between logs.

> Did it happen with 1.4.0? If not, can you please git-bisect it?

Never tried evdev with 1.4.0. I'll try to find it.

Created attachment 15806 [details]
xev output with kbd driver

Created attachment 15807 [details]
xev output with evdev driver

> Did it happen with 1.4.0? If not, can you please git-bisect it?

Just tried 1.4.0 — problem persist. 

(In reply to comment #8)
> > Did it happen with 1.4.0? If not, can you please git-bisect it?
> 
> Just tried 1.4.0 — problem persist. 
> 

Just tried it in master and it works. LWIN + LSHFT + J prints out Cyrillic O in xev as keycode. With both kbd and evdev. So I guess this problem may be fixed, can you please verify this?

> Just tried it in master and it works. LWIN + LSHFT + J prints out Cyrillic O in
xev as keycode. With both kbd and evdev. So I guess this problem may be fixed,
can you please verify this?

I'm afraid, it is not true. I have tried xserver from git and found what a problem is still there. 

By the way, seems what chances to get Cyrillic_O is somehow magically depend on previously entered letters. For example, if you type “jjjjj”, then <LWIN>+<LSHFT>+<J>, you have a better chance to get “J”, than Cyrillic_O. Otherwise, if you type “оооооо” (Cyrillic_o), and then <LWIN>+<LSHFT>+<J>, _may be_ you will get Cyrillic_O.

This is a mass change of bugs. Bugs assigned to me that haven't been updated in the last 3 years are closed as WONTFIX, because, well, let's at least be honest about it.

Please do not re-open unless you have a really good reason to do so (e.g. you're fixing it yourself). If it hasn't been fixed in the last 3 years, it probably won't be fixed anytime soon either. Sorry.