# File wm.rb, line 450
    def tile!
      priCol, secCol, extCol = self[1], self[2], self[3]

      unless priCol.empty?
        # keep only the first client in primary column
          priClient, *rest = priCol.clients
          secCol.unshift! rest

        # squeeze extra columns into secondary column
          if (numAreas = self.indices.length) > 3
            (numAreas - 2).times do
              secCol.concat! extCol
            end
          end

        secCol.mode = :default
        #priCol.mode = :max
        priClient.focus!
      end
    end