I have mapped Insert to Multi_key (also known as Compose) so I can input ä or µ. I've used xmodmap -e 'keycode 118 = Multi_key' in my wm init script.
Now, checking /usr/share/X11/locale/en_US.UTF-8/Compose, I see there are already rules to input Greek letters:
...
<dead_grave> <nobreakspace> : "̀" U0300 # COMBINING GRAVE ACCENT
<dead_greek> <A> : "Α" U0391 # GREEK CAPITAL LETTER ALPHA
<dead_greek> <a> : "α" U03B1 # GREEK SMALL LETTER ALPHA
<dead_greek> <B> : "Β" U0392 # GREEK CAPITAL LETTER BETA
<dead_greek> <b> : "β" U03B2 # GREEK SMALL LETTER BETA
<dead_greek> <D> : "Δ" U0394 # GREEK CAPITAL LETTER DELTA
<dead_greek> <d> : "δ" U03B4 # GREEK SMALL LETTER DELTA
...
Problem is, the dead_greek key does not exist in my layout.
I can either use xmodmap -e 'keycode 118 = dead_greek' to map Insert to it, losing Multi key or I can just somehow use the sequence Multi key + g to register as Dead Greek (losing characters like ğ or ġ, which I'm OK about).
How can I do the latter preferably with one line commands to put in my wm init script?
Note that I do not want to mutate /usr/share/X11/locale/en_US.UTF-8/Compose or create a ~/.XCompose and add all the Greek letter definitions again (since they already exist in the system Compose file)
In short, how to Multi_key+g→dead_greek?
update
For a temporary workaround, based on this post, I was able to map shift+Insert to dead_greek.
xmodmap -e "keycode 118 shift = Multi_key dead_greek"
Weirdly, none of the modifiers listed via xmodmap -pm are usable here except shift, so this was a compromise…
