    # File ../lib/fox/undolist.rb, line 281
        def trimSize(sz)
          if @size > sz
            s = 0
            @undolist.reverse.each_index { |i|
              j = @undolist.size - (i + 1)
              s += @undolist[j].size
              @undolist[j] = nil if (s > sz)
            }
            @undolist.compact!
            @marker = nil if (@marker != nil && @marker > @undolist.size)
          end
        end