Comment 12 for bug 1297051

> Looking at the source, it is necessary to send ESC[?40h

This is the intended behavior, matching xterm and http://invisible-island.net/xterm/ctlseqs/ctlseqs.html

> Answerback does not work

Yup. What would be a practical use for this feature? Note that VTE is not developed along the lines of aiming for 100% coverage of VT100/102/220/whatever... features are rather added when they turn out to be widely used and required, trying to keep things simple in the mean time and getting rid of legacy rarely used hardly useful features. I bet you could find quite a few similar ones that we don't support.