xbindkeys doesn't work in Terminator, but works in other apps

[neckutrek]

Setup:
Ubuntu 20.04.4 LTS (Focal Fossa)
Terminator 1.91
xbindkeys 1.8.6 by Philippe Brochard

Contents of ~/.xbindkeysrc:

"xvkbd -xsendevent -text '{'"
    m:0xc + c:16
    Control+Alt + 7

When I run Terminator and press ctrl+alt+7 no curly brace is inserted.
This works in Chrome, VS Code etc.

$ xvkbd -xsendevent -text '{'
Warning: Cannot convert string "-*-lucidatypewriter-bold-r-*-*-12-*-*-*-*-*-iso8859-1" to type FontStruct
Warning: Cannot convert string "-*-helvetica-bold-r-*-*-12-*-*-*-*-*-iso8859-1" to type FontStruct
Warning: Cannot convert string "-*-helvetica-medium-r-*-*-12-*-*-*-*-*-iso8859-1" to type FontStruct
Warning: Cannot convert string "-*-helvetica-medium-r-*-*-10-*-*-*-*-*-iso8859-1" to type FontStruct

[yagilm]

Same issue with
terminator 2.1.1
xbindkeys 1.8.7
on Ubuntu 22.04

[mattrose]

This would be an issue either with GTK+ or VTE. I can't do anything to fix it, unfortunately.