If I runx <- standard.theme(), the fill variable (x$superpose.symbol$fill) becomes:

"#CCFFFF" "#FFCCFF" "#CCFFCC" "#FFE5CC" "#CCE6FF" "#FFFFCC" "#FFCCCC"

which are the old colour palette, instead of lightened versions of the default new symbol colours. There is thus a mismatch in colours between the symbol and the fill colours. Not sure why the linked line isn't working?