/usr/share/themes/Adept/xfwm4/themerc is in xfwm4-themes 4.10.0-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 | full_width_title=true
button_offset=0
button_spacing=0
title_vertical_offset_active=-2
title_vertical_offset_inactive=-2
button_layout=H|MC
active_text_color=#ffffff
inactive_text_color=#bdbebd
|