The string form of displayWidth() is ignorant about graphemes #1
Description
displayWidth() does not understand e.g. combining characters and the use of ZWJ to accurately provide display width -- it assumes that each dchar can be taken as is.
The technically "correct" would be to to use std.uni to break down the string into graphemes.
Unfortunately, std.uni is also broken for relatively modern graphemes. Still, if this package were to use the grapheme support in std.uni, then when that package got fixed, it would likely do better here. Additionally there are numerous sequences for which std.uni is not broken.