I'm a beginner in Typography (Inkscape and FontForge on Win7x32).
I try to explain my answer with an example:
I like to use the existing OFL font family "PT Sans" with different styles/weights and also Condensed/Extended variants for charts and drawings in a project. But this font-family (like any other good text font) misses some Unicode symbol chars (from Unicode-Block Dingbats, Miscellaneous Symbols, etc.) that I need.
Windows seems to automatically use sometimes weird fallback chars, coming from the installed fonts with extended Unicode support (Segoe UI Symbol, Arial Unicode MS, DejaVu Sans, etc.). Office/Word (Uniscribe?), MS IE (first Uniscribe, now DirectWrite), Firefox (first Uniscribe, now DirectWrite), Chrome (Uniscribe) seem to have sometimes different implementations of this "font fallback mechanism". I was unable to find enough information to understand this OS and software behaviour. I'm especially interested if it is possible to edit this mechanism, for example to prescribe the usage of the preferred Unicode font. This would be generally interesting also by using fonts like Linux Liberation/Biolinum. Here some links:
Wikipedia: Fallback font
http://MS Win UI Dev: Using Font Fallback
Mozilla: Making font initialization lazier
Brett Wilson (Google Chrome Dev) / Uniscribe: The Missing Documentation & Examples
I think I have two options:
A) use the PT Sans fonts and modify/extend them with the risk to have to integrate future releases and to make errors as a beginner
B) create a new font with the PT Sans metrics and only the desired Unicode symbols. But the technical background and the fluid usage in texting/graphical software is not clear to me (without the need to change font family for certain characters in the text).
Is there more information about the Font fallback mechanism with rare Unicode characters in Windows, especially whether this behavior can be influenced?
I hope my question is clear enough and someone here can extend my knowledge about this complex behaviour. Thank you.