line height issues
./build/utils/pango-view --gravity=south --line-spacing=1.0 utils/test-chinese.txt
yields
./build/utils/pango-view --gravity=north --line-spacing=1.0 utils/test-chinese.txt
yields
Similarly for east and west.
So for some reason, with gravity north or west, we get font metrics that have a line height of 0.