When the save slot is disabled, we want it to become
a dropdown only instead of disabling it.

Change-Id: I22fb04c8a0c9afc0a1af8f031a584cdaa99484f9
Reviewed-on: https://gerrit.libreoffice.org/20079Reviewed-by: Samuel Mehrbrodt <Samuel.Mehrbrodt@cib.de>
Tested-by: Samuel Mehrbrodt <Samuel.Mehrbrodt@cib.de>