Vim catching Win-key keyboard shortcuts on XTerm and i3

Question

I am using Vim 8.2 on XTerm(363) and use i3 version 4.19 as window manager on Arch Linux kernel version 5.4.89-1-lts. My i3 modifier key is the Windows key. When I use Win+h, Win+l, Win+k, or Win+j to move one window to the left, right, up, or down; Vim is catching these keyboard shortcuts and rings the terminal bell, when in normal mode, or inserts strange character sequences like the one below, when in insert mode.

<t_<fd>c><t_<fd>b>

<fd> being highlighted in red meaning it is a special character.

It looks like <t_<fd>b> appears when I make the XTerm with Vim the active window using Win+h, Win+j, Win+k, or Win+j and <t_<fd>c> appears when I make a different window the active window using the same keyboard shortcuts when the XTerm with Vim was the active window before.

Also occurs with empty vimrc.

This hasn't happened before this day. How to get rid of it?

Answer 1

Add this to your vimrc:

set t_fd=
set t_fe=

Some terminals including xterm support the focus event tracking feature. If this feature is enabled by the 't_fe' sequence, special key sequences are sent from the terminal to Vim every time the terminal gains or loses focus. Vim fires focus events (|FocusGained|/|FocusLost|) by handling them accordingly. Focus event tracking is disabled by a 't_fd' sequence when exiting "raw" mode. If you would like to disable this feature, add the following to your .vimrc:
set t_fd=
set t_fe=

Quoted from :h xterm-focus-event

Thanks to D. Ben Knoble for pointing me to :help term.txt, which mentions this option