Extended Embed fonts
Calibre's Embed fonts tool only looks in the System Fonts folder.
Not all my fonts are installed ( Limiting the installed set is very good policy to avoid a sluggish Windows system).
What I would like is an 'extension' to the basic feature.
1) Look in the additional locations specified
2) Allow those locations to be classified: eg. Free, NotFree, Licensed (have license for commercial book use)
3) Filter the (allowed) results by #2's classification
The resulting usage could be: embed fonts only from folders classed as Free.