Re: [NTG-context] underbraces get progressively more misaligned (w/ minimal example)

I thought the problem might lie with the general \definemathunderextensible (math-stc.mkvi), because underbrace is defined as \definemathunderextensible [vfenced] [underbrace] ["FE3DF] % ["023DF] Other underextensibles include \underbar: \definemathunderextensible [vfenced] [underbar] ["FE33F] % ["203E] So I tried my example replacing \underbrace with \underbar but the alignment comes out fine (and \overbrace works fine too). So that debugging idea didn't work, except to indicate that something special about underbrace isn't working right. Does anyone have suggestions for further debugging ideas? -Sanjoy