Automatic Font Activation on OS X
OS X Font Book help:
“Automatic font activation: Select this checkbox to enable fonts on your computer whenever they are needed by an application, even if you haven’t installed the fonts using Font Book. For example, if someone sends you a document that uses a font you haven’t installed, but the font is in your Documents folder, Font Book will find and enable the font so the document appears correctly.
NOTE: If you turn off Spotlight searching for any folder or any disk connected to your computer, Font Book can’t find and enable fonts in those locations.”
If you see the “[Application] wants to use the font [x] on the volume [y]. This font is not installed. Allow [application] to use this font?” message on OS X.. it’s the font system working with Spotlight to find fonts that aren’t installed in the usual places, but are present in your computer.
You can turn it on and off in the preferences of Font Book – “Automatic font activation”.
