See https://www.x11vis.org for an introduction.
(Tested on Ubuntu 24.04.)
First, install the build dependencies (xcb-proto) and the cpanminus Perl
package manager:
sudo apt install build-essential cpanminus xcb-proto
Then, install the Perl dependencies (can take a few minutes):
sudo cpanm AnyEvent AnyEvent::Socket Twiggy Dancer IO::All JSON::XS Moose MooseX::Singleton XML::Twig
Afterwards, you should be able to run sudo make install.
See the manual: https://x11vis.org/docs/manual.html
The 'icing' is the one-line summary of the message.
If you'd like to add/improve the summaries for various kinds of messages, look
in the reply_icing, request_icing and event_icing functions of
PacketHandler.pm to improve the presentation of replies, requests or events.