On Tuesday 29 August 2017 14:19:06 Uwe Brauer wrote:
>     > On Monday 28 August 2017 22:25:51 Uwe Brauer wrote:
>     >
>     > ok, i think i solved your problem.
>     > keyboard layout > xkb options
>     >
>     > pick a "compose key position" that suites you
>     > for example left winkey, then....
>     > win+"+a = �
>
> I tried out xev in order to see whats up: when I pressed the key in
> question, It's shift+ the key two keys to the right of L
> having us/international activated I obtained
>
> KeyPress event, serial 39, synthetic, NO, window 0x5a0001
> state 0x2001, keycode 0 (keysym 0xa8, diarersis), same_screen Yes
> XMBLookupstring gives 2 bytel (c2 a8) "�"
>
> Is this helpful?
>
> BTW I obtain the same result for US alt-intl
>

it should have been saying: dead_diaeresis

try
"rm -R ~/.xinput.d"

you can try asking in the ubuntu forum about dead keys and compose keys not 
working.....