Changing font of GtkSourceView changes font of GtkSourceMap

I can't figure out how to change the font of GtkSourceView and
GtkSourceMap in a reasonable way.

According to the documentation, the View and the Map should be using
the same font but with the Map using a font size of 1pt. To me this
implies that when I change the font of the TextBuffer of the View
using tags, I can copy the PangoFontDescription to a new object,
change the font size to 1pt and set the new PangoFontDescription as
the "font-desc" property of the Map.

In practice, however, the Map always has the exact same font size as
the View. No matter what I do, I can't seem to change the font size of
the Map to 1pt, unless I change the font size of the View to 1pt, as
well.

What is the correct processes for changing the font size of both the
View and the Map?

Thank you,
- Mitko