pango_font_description_from_string_relative
Submitted by Behdad Esfahbod
Link to original bug (#562252)
Description
Add api that takes a font_desc and a string, and modifies font_desc according to string. This can be used to parse things like "120%" or "larger" or "bold" or "bolder" that will affect a given font desc. Useful in hierarchical structures and has uses in gtkrc (bug 325767) and pangomarkup (bug 170055).
The details need to fleshed out, but I think this has enough uses to live in pango.