/usr/include/X11/bitmaps/light_gray is in xbitmaps 1.1.1-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | #define light_gray_width 4
#define light_gray_height 2
static char light_gray_bits[] = {
0x08, 0x02};
|