Sadly, I haven’t no time nor skill to write so much useful thing as documentation.

On the other hand, if most of the features are not obvious, at least they’re exposed in the user interface, thus "accessible" for the curious. Unfortunately, there is an area which is not at all exposed in the UI, the scripter. I won’t start document it right now! I just wanted to let you know the very first key (hm, 2 firsts!) of the Fontmatrix Python scripter.

print dir(Fontmatrix)

=>['DB', 'Debug', 'children', 'className', 'connect', 'currentFontFamily', 'currentFontNames', 'currentFontPath', 'currentFontStyle', 'currentFonts', 'deleteLater', 'disconnect', 'help', 'nextFace', 'nextFamily', 'objectName', 'parent', 'previousFace', 'previousFamily', 'quit', 'setParent', 'start', 'terminate', 'updateTree']

print dir(Fontmatrix.DB())

=>['AllFontNames', 'AllFonts', 'Font', 'FontCount', 'Fonts', 'Remove', 'addTag', 'addTagToDB', 'children', 'className', 'connect', 'deleteLater', 'disconnect', 'editTag', 'getTags', 'help', 'insertTemporaryFont', 'objectName', 'parent', 'removeTag', 'removeTagFromDB', 'setParent', 'setTags']

On the contrary, what is documented (in INSTALL file) is the way of enabling scripter at compile time.

HTH