'Screenshot' option of Graphical installer not accessible through keyboard

[Kaartic Sivaraam <kaarticsivaraam91196@gmail.com>]

Hello all,

I recently tried to install Debian 9 using the graphical installer. Due
to some unknown reason my mouse did not work in the graphical
installer. It wasn't a big deal as I could manage well just with my
keyboard BUT I was unable to capture a screen shot of an error as the
option for taking screen shot wasn't accessible through the keyboard
like the 'Continue' and 'Back' options. It would be nice to make it
accessible through the keyboard as it would be helpful in situations
like this.

Thanks, 
Kaartic