"Dynamic" HTML in label of checkboxes

gistfile1.xml

<xh:html xmlns:xh="http://www.w3.org/1999/xhtml"
      xmlns:xf="http://www.w3.org/2002/xforms"
      xmlns:xxf="http://orbeon.org/oxf/xml/xforms"
      xmlns:ev="http://www.w3.org/2001/xml-events"
      xmlns:xs="http://www.w3.org/2001/XMLSchema"
      xmlns:fr="http://orbeon.org/oxf/xml/form-runner">
    <xh:head>
        <xf:model>
            <xf:instance>
                <gaga>1</gaga>
            </xf:instance>
            <xf:bind ref="/gaga" relevant=". > 1"/>
        </xf:model>
    </xh:head>
    <xh:body>
        <xf:trigger>
            <xf:label>Click me</xf:label>
            <xf:setvalue event="DOMActivate" ref="." value=". + 1"/>
        </xf:trigger>
        <xf:group ref=".">
            <xf:select ref="." appearance="full">
                <xf:item>
                    <xf:label>
                        <xh:b>bold</xh:b>
                        <xf:output value="."/>
                    </xf:label>
                    <xf:value>2</xf:value>
                </xf:item>
            </xf:select>
        </xf:group>
    </xh:body>
</xh:html>