/etc/X11/app-defaults/Xcolors is in xcolors 1.5a-8.
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 11 12 13 14 | *Label.Font: 5x7
*panes.Width: 985
*Text*Height: 50
*viewport*allowVert: true
*sample*String: \
Button 1 sets the text color, button 2 sets the background.\n\
Press q to quit. You can also type new text here.
*Label*Translations: #override \
<Btn1Up>: set-foreground()\n\
<Btn2Up>: set-background()\n
*Box*baseTranslations: #override \
<Key>q: quit()\n
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