This was once an experiment that allowed this (there’s even a gif of it)
But my plugin injected itself into the internal Coda client app apis, which is unsafe, could bring Coda extra problems, and is generally against ToS.
While I agree having this would be cool, I’m not so sure this is conceptually right to do. At the same time, I believed Canvas columns were conceptually not right for Coda, yet now we have them.