Hostname in X11 window title
This depends on shell configuration and the exact terminal involved; most things support XTerm Control Sequences though terminals can be configured to deny the use of those escape sequences. What Linux systems often have is shell configuration (usually under /etc/profile.d) that automatically runs the escape sequence to set the title to the hostname. This can also be done manually:

printf "\033]2;this is a test\007"


which should set the title



if not, you'll need to configure the terminal to allow that escape sequence, which will be under the preferences or in a configuration file somewhere, depending.

This can be done automatically from a shell configuration file by generating the appropriate escape sequence with the hostname (or whatever other data you might want):

printf "\033]2;%s\007" $(hostname)