X11 was still initializing a blank map to 'stone' instead of to
'unexplored'. When the core started forcing 'unexplored' as part
of cls(), you could see the S_stone background show up and then be
overwritten with S_unexplored.
Also, X11 is [still] drawing unused column 0. That was also 'stone'
but has been changed to 'nothing' so is now blank for both tiles map
and text map (regardless of S_unexplored value). The extra useless
column doesn't look too bad normally but does if a vertical scroll
bar is added to support a clipped map.
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