Any chance of a x mins before fade warning ...I'd go for the x seconds before fade warning, 15 seconds should be enough to press Ctrl-S once more
Why should we need those additional seconds? The fader does not interfere with the ongoing work.
We can still do anything when the desktop is fading (before it becomes too illegible, of course).
BTW, you may consider below options:
1) choose a bigger value for fade duration
: then you don't have to press Ctrl-S in a haste
2) choose a smaller value for maximum opacity
: then you can simply ignore the fader when it's shown