Gfilui

For years I used the following ~/.Xmodmap file to get german umlauts quickly, e.g. when I press the ALT_R + a I get ä. A nice shortcut compared to using the compose key:

keycode 108 = Mode_switch
keycode 38 = a A adiaeresis Adiaeresis adiaeresis Adiaeresis
keycode 30 = u U udiaeresis Udiaeresis udiaeresis Udiaeresis
keycode 32 = o O odiaeresis Odiaeresis odiaeresis Odiaeresis
keycode 39 = s S ssharp ssharp ssharp ssharp
keycode 20 = minus underscore endash endash endash endash
keycode 60 = period greater ellipsis ellipsis ellipsis ellipsis
keycode 61 = slash question emdash emdash emdash emdash

Note: I'm using the Happy Hacker Keyboard, which has no ALT_GR key. The keycode 108 is sent by the right ALT key and Mode_switch generally corresponds to the 2nd and 3rd values above.

Since 17.10 all combinations only result in a warning sound, nothing else happens. I noticed the same on Fedora 27, so maybe it's related to new xkb settings and / or Gnome Shell?

Any ideas how I can archiev this under current Gnome Shell setups?

Thanks to Gunnar Hjalmarsson, I found enough information in this answer. Here's what I did:

To include some new key settings, I added this to the end of /usr/share/X11/xkb/symbols/us:

partial alphanumeric_keys
xkb_symbols "us-de" 

 // include all the definitions from us(basic), I just want to add to it

 include "us(basic)"
 name[Group1]= "English (US, with german umlauts)";

 // add german umlauts

 key <AC01> [ a, A, adiaeresis, Adiaeresis ] ;
 key <AD07> [ u, U, udiaeresis, Udiaeresis ] ;
 key <AD09> [ o, O, odiaeresis, Odiaeresis ] ;
 key <AC02> [ s, S, ssharp, ssharp ] ;

 // and some other keys

 key <AE11> [ minus, underscore, endash, endash ] ;
 key <AB09> [ period, greater, ellipsis, ellipsis ] ;
 key <AB10> [ slash, question, emdash, emdash ] ;

 // have ALT_R as level 3 switch

 include "level3(ralt_switch)"
;

And to have a variant I can select from Settings > Region & Language, I added
the following to the end of the variantList for English (US) in this XML
file /usr/share/X11/xkb/rules/evdev.xml:

<variant>
<configItem>
 <name>us-de</name>
 <description>English (US, with german umlauts)</description>
</configItem>
</variant>

After a sudo systemctl restart keyboard-setup.service I could select the new
layout variant from Settings > Region & Language.