texmath-0.6.7: tests/writers/munder9.tex
\underset{\ddddot{} }{{x}} \neq \underset{\ddddot{} }{{x}} =\underset{\ddddot{} }{{x}} =\underset{\ddddot{} }{{x}}\underset{\ddddot{} }{{x}} \neq \underset{\ddddot{} }{{x}} =\underset{\ddddot{} }{{x}} =\underset{\ddddot{} }{{x}}