"Show invisibles" font feature -- is it useful?


We (WSTech) are leaning toward removing the “Show Invisible” feature from future releases of SIL fonts. Your input on this decision is invited – and we anticipate wrapping up the discussion within the next 2 weeks.


For several years, a number of SIL fonts have included a feature called “Show Invisibles” that tries to provide visible glyph for some characters that are normally not visible, for example characters like the combining grapheme joiner, zero width joiner and soft hyphen.

Note that this is distinct from the capability of some applications (such as Microsoft Word) to show/hide control characters. Rather I’m talking about a user-selectable font feature that substitutes a visible outline for glyphs that normally don’t have such.

One question is whether anyone is successfully using this feature to help solve real-world problems or not?

It has always been the case that whether or not the Show Invisibles feature works and, if so, exactly which characters can actually become visible, is highly dependent on the application that is using the font. As rendering technology has evolved we are finding that this feature no longer works in applications it once did, or the characters for which the feature does work are fewer in number. As examples: in Firefox the feature no longer works at all and in LibreOffice Writer some of the characters still show up but others don’t. Further, the results for Graphite and OpenType rendering are very different. With all this variability, it is hard to even document the feature much less help folks when it isn’t working for them.

In some ways it feels like we, as font developers, are fighting a losing battle. So the question is whether we should fight it for the remaining environments that partially work, or can we just remove the feature from future versions of our fonts?

Feel free to respond in this forum or, if you prefer, to me privately.

Bob Hallissy