/usr/share/themes/Default-4.2/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 9 10 | active_text_color=#FFFFFF
button_offset=-1
button_spacing=0
full_width_title=true
maximized_offset=2
title_horizontal_offset=8
title_shadow_active=true
title_shadow_inactive=false
title_vertical_offset_active=1
title_vertical_offset_inactive=1
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