U+0335 to U+0338 do not visually combine with the p
This has been reported to the Debian BTS by Thibaut Girka email@example.com: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=912282
In Gtk3 applications such as gucharmap, combining characters U+0335 to U+0338 do not visually combine to the previous character. Because of this, since they have null width, they visually combine with the next character.
E.g., “a̸” should show as a with a “long solidus” (U+0338) overlayed, but this is overlayed to the next character instead.
This does not occur with other fonts such as those of the DejaVu family.