Lots of people do need 'foreign' language fonts now and then. So if we wanted to do what Explorer does and 'hide' some 'foreign-language' fonts, we would of course need an option for that. I can confirm that when I untick the option to hide fonts based on language settings, this string value no longer exists, so it should be possible to just read this value and use it to indiscriminately filter the font list, I think. On my system, the content of that value is: However, I did find out that the hidden fonts are available from the 'HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Font Management' key in the string value 'Inactive Fonts'. 'In Windows 7, there are no APIs for directly querying which fonts are hidden, or for setting fonts to be hidden.'
