Bug 655926 – x11-terms/gnome-terminal fails to respond to control codes enabling VT220 emulation and application keypad mode

• Product: Gentoo Linux
• Status: UNCONFIRMED ---

[Description Matthew "Archer" Vaughn 2018-05-17 01:41:08 UTC]

Created attachment 531870 [details]
emerge --info x11-terms/gnome-terminal

According to upstream (https://bugzilla.gnome.org/show_bug.cgi?id=566430), gnome-terminal should respond to control codes enabling VT220 emulation and application keypad mode, and thereby emit escape sequences for the keypad in application keypad mode that are distinct from those with application keypad mode disabled (http://invisible-island.net/xterm/ctlseqs/ctlseqs.html#h2-VT220-Style-Function-Keys).

Using the latest gnome-terminal on gentoo, I'm unable to get it to emit those codes. I need the application keypad functionality to work with tmux, vi, and other programs that expect distinct character sequences from these keys; otherwise, they are not distinguishable from their counterparts elsewhere on the keyboard (e.g., keypad insert and editor insert produce identical sequences).

As an example of what is expected when typing the keypad '0' key with NumLock off:
% > cat -v
^[[2~
% > printf '\033[?1061h\033='; cat -v
^[Op

As an example of what I observe instead:
% > cat -v
^[[2~
% > printf '\033[?1061h\033='; cat -v
^[[2~

The control codes '\033[?1061h\033=' should be sufficient to enable VT220+AppKeypad, but in gnome-terminal they have no effect. The expected result is obtainable in xterm, but gnome-terminal is preferable.