re #8753: Remove the background from the used monitor

Correct a bug found that only monitor 1 was being used. But, it ought to
use the monitor defined inside the mask file.

As a minor thing, remove the sans_reduction_steps.Normalize inheritance,
because it was not adding anything for this class.
re #8753: Correct the misspelling of the back syntax
re #8753: Add unit test for back syntax
Merge remote-tracking branch 'origin/bugfix/8753_back_syntax'