    # File ../lib/fox/undolist.rb, line 132
        def add(command, doit=false)
          # Cut redo list
          cut

          # No command given?
          return true if (command == nil)

          # Add it to the end of the undo list
          @undolist.push(command)

          # Execute it right now?
          command.redo if doit

          # Update size
          @size += command.size     # measured after redo

          # Update the mark distance
          @marker = @marker + 1 if (@marker != nil)

          # Done
          return true
        end