def label(lang=nil)
      label = @doc.elements['/manifest/application'].attributes['label']
      if label.nil?
        # application element has no label attributes.
        # so looking for activites that has label attribute.
        activities = @doc.elements['/manifest/application'].find{|e| e.name == 'activity' && !e.attributes['label'].nil? }
        label = activities.nil? ? nil : activities.first.attributes['label']
      end
      unless @rsc.nil?
        if /^@(\w+\/\w+)|(0x[0-9a-fA-F]{8})$/ =~ label
          opts = {}
          opts[:lang] = lang unless lang.nil?
          label = @rsc.find(label, opts)
        end
      end
      label
    end
def label(lang=nil)
      label = @doc.elements['/manifest/application'].attributes['label']
      if label.nil?
        # application element has no label attributes.
        # so looking for activites that has label attribute.
        activities = @doc.elements['/manifest/application'].find{|e| e.name == 'activity' && !e.attributes['label'].nil? }
        label = activities.nil? ? nil : activities.first.attributes['label']
      end
      unless @rsc.nil?
        if /^@(\w+\/\w+)|(0x[0-9a-fA-F]{8})$/ =~ label
          opts = {}
          opts[:lang] = lang unless lang.nil?
          label = @rsc.find(label, opts)
        end
      end
      label
    end
application label
 @param [String] lang language code like 'ja', 'cn', ...
 @return [String] application label string(if resouce is provided), or label resource id
 @return [nil] when label is not found
 @since 0.5.1