Ah, I'm using the theme "Theme.Holo.Light", which has light text on inactive buttons and dark text on active buttons, but Button.TextColor always reads the same value whether active or not.
I do need to manually set the text color of one of my buttons though, and when it's inactive I manually set it to Colors.LightGrey, which seems right compared to my other buttons that are colored by the theme, I just wanted to instead try to set that color to the color of another inactive button instead of Color.LightGrey, as then if I changed the theme, it would just work, intead of me having to change that Color.LightGrey to Color.WhateverTheNewThemeInactiveTextColorIs.
I can't seem to do that though - programatically determine the text color of an inactive button as dictated by the theme.