How to use a binding instead of a row in a grid

Question

In a Xulrunner application I'm working on a grid with a dynamic number of rows. All the rows are going to look similar with same functionality. For this reason I would like to create and reuse an XBL binding, that would represent a row in my grid. Unfortunately binding's content doesn't seem to register as separate cells of the grid (see picture). Is it possible to use a binding to serve as a row element? If yes, how to achieve the desired effect?

grid.xul:

<grid class="grid-with-borders">
  <rows>
    <row>
      <label value="Column1"/>
      <label value="Column2"/>
      <label value="Column3"/>
      <label value="Column4"/>
    </row>
    <my-row/> <!-- This is the binding -->
  </rows>
  <columns mousethrough="always">
    <column flex="1" style="width: 150px;"/>
    <column flex="1" style="width: 150px;"/>
    <column flex="1" style="max-width: 200px;"/>
    <column flex="1" style="max-width: 150px;"/>
  </columns>
</grid>

my-row.xml:

<binding id="my-row">
  <content>
    <xul:label value="Cell11"/>
    <xul:menulist label="Cell12">
      <xul:menupopup>
        <xul:menuitem value="0" label="Zero"/>
        <xul:menuitem value="1" label="One"/>
        <xul:menuitem value="2" label="Two"/>
      </xul:menupopup>
    </xul:menulist>
    <xul:label value="Cell13"/>
    <xul:label value="Cell14"/>
  </content>
</binding>