How to make a ISO_Level4_Shift and Lock in xkb?

It's possible but a bit hacky. No specific keysyms are already defined. ISO_Level3_{Shift,Latch,Lock} (and the same three for level5) are defined in X11 and libxkbcommon headers at compile time.

At runtime, they are activated in the compatibility module via interpret stanzas and actions; for example, examine your current keymap:

$ xkbcomp $DISPLAY - | less //.... xkb_compatibility "complete+ledcaps(shift_lock)" { //.... interpret ISO_Level3_Shift+AnyOf(all) { virtualModifier= LevelThree; useModMapMods=level1; action= SetMods(modifiers=LevelThree,clearLocks); }; interpret ISO_Level3_Latch+AnyOf(all) { virtualModifier= LevelThree; useModMapMods=level1; action= LatchMods(modifiers=LevelThree,clearLocks,latchToLock); }; interpret ISO_Level3_Lock+AnyOf(all) { virtualModifier= LevelThree; useModMapMods=level1; action= LockMods(modifiers=LevelThree); }; //.... interpret ISO_Level3_Shift+AnyOfOrNone(all) { action= SetMods(modifiers=LevelThree,clearLocks); }; interpret ISO_Level3_Latch+AnyOfOrNone(all) { action= LatchMods(modifiers=LevelThree,clearLocks,latchToLock); }; interpret ISO_Level3_Lock+AnyOfOrNone(all) { action= LockMods(modifiers=LevelThree); }; //.... 

There is an existing ISO_Level2_Latch keysym. It does not have existing compatibility interpret stanzas like the above, but if you add them it operates as you'd expect. (Shift is already there so ISO_Level2_Shift is unnecessary; Shift_Lock or Caps_Lock takes the place of ISO_Level2_Lock.) So if you wanted a Shift_Latch key, use the ISO_Level2_Latch keysym and add these to your keymap:

 interpret ISO_Level2_Latch+AnyOf(all) { useModMapMods=level1; action= LatchMods(modifiers=Shift,clearLocks,latchToLock); }; interpret ISO_Level2_Latch+AnyOfOrNone(all) { action= LatchMods(modifiers=Shift,clearLocks,latchToLock); }; 

We can use this sort of approach for levels 4, 6, 7 and 8, but there are no predefined keysyms for ISO_Level4_Shift et al. You could add them to the code and recompile, or you could repurpose some unused keysym and interpret it as if it were a level4 shift (or latch, or lock). Examining header files in libxkbcommon we find all the keysym names XKB knows about; these look like they might suit our purposes:

//....in xkbcommon/xkbcommon-keysyms.h: //.... #define XKB_KEY_ISO_Fast_Cursor_Left 0xfe2c #define XKB_KEY_ISO_Fast_Cursor_Right 0xfe2d #define XKB_KEY_ISO_Fast_Cursor_Up 0xfe2e #define XKB_KEY_ISO_Fast_Cursor_Down 0xfe2f 

Remove the XKB_KEY_ prefix to get keysym names we can reference in XKB rules. Let's use ISO_Fast_Cursor_Left to fake ISO_Level4_Latch.

First, generate a basic keymap, with setxkbmap -print; then we'll edit this file and add overrides to it, and finally load the altered keymap with xkbcomp [file] $DISPLAY:

$ setxkbmap -print > mykeymap.xkb xkb_keymap { xkb_keycodes { include "evdev+aliases(qwerty)" }; xkb_types { include "complete" }; xkb_compat { include "complete" }; xkb_symbols { include "pc+us(altgr-intl)+inet(evdev)" }; xkb_geometry { include "pc(pc105)" }; }; 

Now edit this file and place the overrides we need into it:

// Attempting to define and use a key as Level4 Shift/Latch/Lock. // Plan: * activate lv5 shift on rctrl. // * place latches on lv5 of keys 2,3,4,5 for corresponding level. // * replace keys ASDF with 8-level versions and define symbols for test. // * pressing RCtrl+4 then A should result in Á // starting point: setxkbmap -layout us -variant altgr-intl -option '' -print // load this file: xkbcomp myfile.xkb $DISPLAY xkb_keymap { xkb_keycodes { include "evdev+aliases(qwerty)" }; xkb_types { include "complete" }; xkb_compat { include "complete" // add in interpretations // ISO_Level3_Latch includes a +AnyOf stanza and a +AnyOfOrNone stanza (same for ISO_Level5_Latch) // assume each additional latch needs both interpret ISO_Level2_Latch+AnyOf(all) { useModMapMods=level1; action= LatchMods(modifiers=Shift,clearLocks,latchToLock); }; interpret ISO_Level2_Latch+AnyOfOrNone(all) { action= LatchMods(modifiers=Shift,clearLocks,latchToLock); }; interpret ISO_Fast_Cursor_Left+AnyOf(all) { // Level4 needs both Shift and LevelThree useModMapMods=level1; action= LatchMods(modifiers=Shift+LevelThree,clearLocks,latchToLock); }; interpret ISO_Fast_Cursor_Left+AnyOfOrNone(all) { // Level4 needs both Shift and LevelThree action= LatchMods(modifiers=Shift+LevelThree,clearLocks,latchToLock); }; }; xkb_symbols { include "pc" include "us(altgr-intl)" include "inet(evdev)" // latch keys key <AE02> { type= "EIGHT_LEVEL", symbols[Group1]= [ 2, at, twosuperior, dead_doubleacute, ISO_Level2_Latch, X, z, Z ] }; key <AE03> { type= "EIGHT_LEVEL", symbols[Group1]= [ 3, numbersign, threesuperior, dead_macron, ISO_Level3_Latch, X, z, Z ] }; // no ISO_Level4_Latch so use ISO_Fast_Cursor_Left key <AE04> { type= "EIGHT_LEVEL", symbols[Group1]= [ 4, dollar, currency, sterling, ISO_Fast_Cursor_Left, X, z, Z ] }; key <AE05> { type= "EIGHT_LEVEL", symbols[Group1]= [ 5, percent, EuroSign, dead_cedilla, ISO_Level5_Latch, X, z, Z ] }; // no ISO_Level6_Latch so use ISO_Fast_Cursor_Right // no ISO_Level7_Latch so use ISO_Fast_Cursor_Up // no ISO_Level8_Latch so use ISO_Fast_Cursor_Down // eight-level keys ASDF for testing key <AC01> { type= "EIGHT_LEVEL_SEMIALPHABETIC", symbols[Group1]= [ a, A, aacute, Aacute, agrave, Agrave, aring, Aring ] }; key <AC02> { type= "EIGHT_LEVEL_SEMIALPHABETIC", symbols[Group1]= [ s, S, ssharp, section, ccedilla, Ccedilla, ntilde, Ntilde ] }; key <AC03> { type= "EIGHT_LEVEL_SEMIALPHABETIC", symbols[Group1]= [ d, D, eth, ETH, thorn, THORN, t, T ] }; key <AC04> { type= "EIGHT_LEVEL_SEMIALPHABETIC", symbols[Group1]= [ f, F, eacute, Eacute, x, X, z, Z ] }; // ISO_Level3_Shift on Right Alt include "level3(ralt_switch)" // ISO_Level5_Shift on Right Ctrl include "level5(rctrl_switch)" }; xkb_geometry { include "pc(pc105)" }; }; 

Now you can test the latches (in the example above, ISO_Level5_Shift should be the Right Ctrl key; rerun the xkbcomp command if it is not):

• ISO_Level5_Shift+2 then a should print A
• ISO_Level5_Shift+3 then a should print á
• ISO_Level5_Shift+4 then a should print Á
• ISO_Level5_Shift+5 then a should print à

In testing, I've noticed the RCtrl-as-level5-shift is a little flaky and doesn't always get applied properly. Usually rerunning the xkbcomp command once or twice will get it working properly. Test with the A or F keys; Ctrl+D will probably exit your shell.

Some applications will not recognize our borrowed keysym and may do strange things. For example, Firefox will print the 4 even while activating the proper latches, so the key sequence rctrl+4 then a results in 4Á; this does not happen for the real keysyms on 3 and 5, so maybe borrowing a different keysym will let Firefox recognize that nothing should be printed. So far most terminal applications are operating as expected.

I ran into the same problem and found a more straight forward way to do this. My use case was to get a shortcut to level 7 with just one key press, and the method is very general and not a hack.

For the extra level names, we can use the virtual modifiers Super or Hyper (or Meta), in addition to the already used Shift, LevelThree and LevelFive. I will use Hyper for level 7. The interpretations for Super and Hyper are defined in /usr/share/X11/compat/misc, and they are included in the default configuration.

To add the extra shortcut, we shall create a new type. The type typically used for eight levels is EIGHT_LEVEL, and is defined in /usr/share/X11/xkb/types/level5. Create a file called level7_hyper with the following content and save it in /usr/share/X11/xkb/types. We can have several key combinations for the same level if we wish.

default partial xkb_types "default" { // Adds the shortcut Hyper to reach level 7 // and Hyper+Shift to reach level 8 virtual_modifiers LevelThree, LevelFive, Hyper; type "EIGHT_LEVEL_HYPER" { modifiers = Shift + LevelThree + LevelFive + Hyper; map[None] = Level1; map[Shift] = Level2; map[LevelThree] = Level3; map[Shift+LevelThree] = Level4; map[LevelFive] = Level5; map[Shift+LevelFive] = Level6; map[Hyper] = Level7; map[LevelThree+LevelFive] = Level7; map[Shift+Hyper] = Level8; map[Shift+LevelThree+LevelFive] = Level8; level_name[Level1] = "Base"; level_name[Level2] = "Shift"; level_name[Level3] = "Alt Base"; level_name[Level4] = "Shift Alt"; level_name[Level5] = "X"; level_name[Level6] = "X Shift"; level_name[Level7] = "X Alt Base"; level_name[Level8] = "X Shift Alt"; }; }; 

To use this type in a symbols file, modify this minimal working example. Save it as e. g. /usr/share/X11/xkb/symbols/level7se.

default partial alphanumeric_keys xkb_symbols "level7se" { // Include your favourite symbols include "se" name[Group1]="Level7-se"; key.type[Group1] = "EIGHT_LEVEL_HYPER"; // Copy in the lines from the symbols file of your choice and make // your edits, here just the button A key <AC01> { [ a, A, b, B, c, C, d, D ]}; // Modifier keys only have one level key.type[Group1] = "ONE_LEVEL"; // Right Alt gives level 3 key <RALT> {[ ISO_Level3_Shift ]}; // Left Win key gives level 5 key <LWIN> {[ ISO_Level5_Shift ]}; // The button to the left of the number line (paragraph on Swedish // keyboards. Tilde on some others?) gives level 7. key <TLDE> {[ Hyper_R ]}; }; 

You then load the configuration with

setxkbmap -types complete+level7_hyper level7se 

We needed to include the complete type as well, since the modifier keys use the ONE_LEVEL type.

To get more level shortcuts, just add the respective lines to the type file and a corresponding section to the symbols file.