Tried a couple ways to initialize a pango font description attribute. None succeeded in such a way that the font description could actually be set.

>>> desc = Pango.FontDescription("monospace 12")
>>> attr = Pango.AttrFontDesc(desc=desc)
Traceback (most recent call last):

+ Trace 229601

>>> Pango.AttrFontDesc.new(desc)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: type object 'AttrFontDesc' has no attribute 'new'
>>> attr = Pango.AttrFontDesc()
>>> attr.desc = desc
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
RuntimeError: unable to set value for field
>>>