You know, fonts are instructions to tell a font rendering engine, how to draw a character on a screen, <br>so the font needs to have support for that language. If it does not, then it's up to the font rendering engine to come up with something, for example if Malayalam is not supported by font X, but is supported by font Y, then even if you want font X, it overlays those characters with font Y, so that it can render something. The font mechanism in Gnome is extremely good about this, KDE is also pretty good about this, not sure about Windows. Some applications like Firefox have their own font rendering mechanism, because they need to be able to make sense of international sites that could have OS unsupported languages in them. <br>