Languages like Khmer and Thai do not put spaces between words. However, to facilitate line-breaking in web pages, lots (most?) such text gets entered with a ZWSP (zero-width space, U+200B) separating words.
Because it has no width, making ZWSP visible requires either changing a line's width (as MS Word does) or changing part of the background color of the adjoining characters (as OpenOffice Writer does; I attach a screen capture of how this).
Since those are word-processors, they present other difficulties when editing XML or HTML containing Khmer. It would be great if Scintilla and programs that make use of Scintilla were able to include ZWSP when making whitespace or non-printing characters visible.
rsperberg at gmail