When using a combination of english (us) layout with another layout such as slovak (sk), the shortcut for switching keyboard layout win + space doesn't work as intended. Switching from us -> sk works, however once sk layout is set, win + space will not toggle sk back to us.
I have so far reproduced the issue with us + {sk, cz, pl} layouts.

Steps to reproduce:
1. Set a combination of english layout (us for instance) and another layout (tested sk, cz, pl). Use win_space_toggle for switching layout.

setxkbmap -layout us,sk -option grp:win_space_toggle

2. Attempt to switch back and forth between the two layouts using win + space.

Observed behavior:
Once sk layout is set, the win + space shortcut will not switch back to us.

Expected behavior:
win + space should toggle between the two layouts in both directions.

Workaround 1:
When setting english layout as second (setxkbmap -layout sk,us), the win + space shortcut switches in both directions. If english layout is desired to be as primary, this is obviously less than ideal.

Workaround 2:
Removing the line defining <SPCE> symbol in /usr/share/X11/xkb/symbols/{sk,cz,pl} allows one to use win + space toggle in both directions with english layout being the primary. This obviously breaks any other type of space symbol (such as non-breaking space) if defined.


My initial impression was that perhaps when sk layout is active, the "nobreakspace" character was pressed instead of regular "space" when pressing win + space toggle. This is not the case as xev always reports "space" character when win + space toggle is pressed, regardless of layout. In addition, cz layout doesn't contain nobreakspace in <SPCE> definition, but also shows the same symptoms when attempting to toggle from cz to us.

Output of setxkbmap -print:
xkb_keymap {
        xkb_keycodes  { include "evdev+aliases(qwerty)" };
        xkb_types     { include "complete"      };
        xkb_compat    { include "complete"      };
        xkb_symbols   { include "pc+us+sk:2+inet(evdev)+group(win_space_toggle)+level3(ralt_switch)+terminate(ctrl_alt_bksp)"        };
        xkb_geometry  { include "pc(pc105)"     };
};