Where is the default Compton configuration file

[ouroumov]

See this:

Can I use my own compton conf file?

By browsing the code on Bitbucket it appears you can simply override the default compton conf by dropping yours in ~/.config/marco-compton.conf Here are the relevant lines from the source: # Allow users to override the defaults by creating their own config # for this wrapper. if [ -f ${HOME}/.config/${WM}-compton.conf ]; then compton \ --config ${HOME}/.config/${WM}-compton.conf & else compton \ [...] Cheers

There is no default Compton file, Compton is invoked by MATE Tweak passing every configuration option on the command line .