Comment 22 for bug 1755106

https://pastebin.ubuntu.com/p/nrtyQZMPdB/

In my case the primary key is the ALT, actually the left alt.

As far as I know, no usage collision of alt-ctrl-g, alt-ctrl-backspaces, ...

I do not use any other setting manager. The problem is ther if I do it 'by hand' in Unity control center. However normally I set up almost everything with script, here is the shortcut setting part:

CK='/org/gnome/settings-daemon/plugins/media-keys/custom-keybindings'
DCONFWRITE='dconf write '
DCONFWRITE+="${CK}"
${DCONFWRITE}/custom0/name "'unset'"
${DCONFWRITE}/custom0/command "'unset'"
${DCONFWRITE}/custom0/binding "'unset'"
${DCONFWRITE}/custom0/name "'gnome-terminal --geometry=80x99-0+0'"
${DCONFWRITE}/custom0/command "'gnome-terminal --geometry=80x99-0+0'"
${DCONFWRITE}/custom0/binding "'<Primary><Alt>g'"
${DCONFWRITE}/custom1/name "'unset'"
${DCONFWRITE}/custom1/command "'unset'"
${DCONFWRITE}/custom1/binding "'unset'"
${DCONFWRITE}/custom1/name "'gnome-session-quit --power-off'"
${DCONFWRITE}/custom1/command "'gnome-session-quit --power-off'"
${DCONFWRITE}/custom1/binding "'<Primary><Alt>BackSpace'"
${DCONFWRITE} "['${CK}/custom0/','${CK}/custom1/']"
unset DCONFWRITE
unset CK

However, the problem is still there, if I do it by hand, and during the debug command the setting is recorded only and it comes to alive after a logout/login cycle.

I am ready to make further experiments, no comes the CTRL+SHIFT instead of CTRL+ALT, how you have just suggested, ... many thanks.