Don't shift the position of the predict/cancel buttons when generating text

[BugReporterZ]

A usability issue is that the position of the predict/cancel/regenerate buttons shifts around depending on the current app state. This makes them somewhat annoying to use with the mouse when there's a need to repeatedly use them.

[lmg-anon]

That's a good point, I think it would be better to just show all the buttons at all times. I did this change in 2c89041.