id	summary	reporter	owner	description	type	status	priority	milestone	component	version	severity	resolution	keywords	cc
308	Glyph substutition does not work for certain character sets.	Alex Taylor		"In principle, when rendering Unicode text, characters that are not supported by the current font will be substituted from a font which does support them.  (Whether Qt4 does this via fontconfig or something else I'm not certain.)

This does work for many languages, including Cyrillic, Hebrew and Greek.  However, it does not work with some other languages, in particular Japanese and Chinese: all relevant characters are rendered with the font's .notdef glyph.

Consequently, when reading text that includes such languages, it is necessary to set the font explicitly to one which supports those languages.  Unfortunately, not all applications allow this (especially web browsers which use page-defined fonts).

You can easily see this by opening a page like https://en.wikipedia.org in the Arora browser.  The list of languages down the left-hand side shows several with substituted characters (specifically: Georgian, Korean, Japanese and Chinese).  "	defect	closed	major		General	4.7.3	low	wontfix