What I actually want to do is do two things, the first is apply this
choose if the first part of the element contains Home before the ::
(effectively ignoring the :: and foo)

<xsl:choose>
		<xsl:when test="($tabName = 'Home')">home</xsl:when>
		<xsl:otherwise>detachFocus</xsl:otherwise>
</xsl:choose>

Then use a similar test to ask if Home is present followed by :: then
find out what is foo

test="contains(@name,'::')"