Package xscope

X Window Protocol Viewer

http://cgit.freedesktop.org/xorg/app/xscope/

xscope sits in-between an X11 client and an X11 server and prints the contents
of each request, reply, error, or event that is communicated between them.
This information can be useful in debugging and performance tuning of X11
servers and clients.

General Commands
Command Description
xscope X Window Protocol Viewer