I have not experimented with this setting, but according to the documentation, the focusedTextColor field on the buttongroup should be working.
optiondialog.ButtonGroup.focusedTextColor = "0xFFFFFFFF"
Are you using a custom font for the button text? That could be causing it not to work.
No, I don't use Custom Font. I tried the same as per Document mention. My Example is here. But no luck.
I managed to make this by using a darker white
dialog.buttonGroup.textColor = "0xFFFFFFFF" dialog.buttonGroup.focusedTextColor = "0xDDD9D7FF". 'darker white (shows as white)
hope it helps
