I would imagine first you have your menu in a xsl:for-each tag so you can loop through each menu node, while in a for-each you have access to the "position()" of a node, this is a standard function not specific to any kind of xml node, but as you can imagine it allows you to get the position in a node-set of a found node.

A practical use would be as such:

<xsl:for-each select="$menuNodes">
 <!-- using a variable here to make the markup below clearer, this will contain the value of the class -->
 <!-- the first line adds the "first" class -->
 <!-- the second line adds the "last" class -->
 <!-- the third line adds the "selected" class, this logic is very basic if the currentPage id is the same as the current menu node id then we have a winner :)-->

 <xsl:variable name="classValue">
   <xsl:if test="position() = 1">first </xsl:if>
   <xsl:if test="position() = last()">last </xsl:if>
   <xsl:if text="$currentPage/@id = ./@id">selected</xsl:if>
 </xsl:variable>
 <li>
    <!-- only add a class attribute if we have anything to show from the variable above, cleaner HTML code, yay... -->
    <xsl:if test="string-length($classValue) &gt; 0">
      <xsl:attribute name="class"><xsl:value-of select="$classValue" /></xsl:attribute>
    </xsl:if>
    <!-- whatever you want to display in your li tag goes here -->
  </li>
</xsl:for-each>

You can combine the above ideas in the logic in the classValue to get the kind of class name you're looking for, I hope this helped you find your solution (if so mark it :) ).

Jamies answer is spot on, but I noticed it didn't contain the selected - 1 / selected + 1 functionality you asked for, so I've expanded his solution to accomodate this.

Below you'll find an xslt-file ready to use with the runway example, in the homepage template and second level textpages:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE xsl:stylesheet [ <!ENTITY nbsp "&#x00A0;"> ]>
<xsl:stylesheet 
<span style="white-space: pre;">  </span>version="1.0" 
<span style="white-space: pre;">  </span>xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
<span style="white-space: pre;">  </span>xmlns:msxml="urn:schemas-microsoft-com:xslt"
<span style="white-space: pre;">  </span>xmlns:umbraco.library="urn:umbraco.library" xmlns:Exslt.ExsltCommon="urn:Exslt.ExsltCommon" xmlns:Exslt.ExsltDatesAndTimes="urn:Exslt.ExsltDatesAndTimes" xmlns:Exslt.ExsltMath="urn:Exslt.ExsltMath" xmlns:Exslt.ExsltRegularExpressions="urn:Exslt.ExsltRegularExpressions" xmlns:Exslt.ExsltStrings="urn:Exslt.ExsltStrings" xmlns:Exslt.ExsltSets="urn:Exslt.ExsltSets" 
<span style="white-space: pre;">  </span>exclude-result-prefixes="msxml umbraco.library Exslt.ExsltCommon Exslt.ExsltDatesAndTimes Exslt.ExsltMath Exslt.ExsltRegularExpressions Exslt.ExsltStrings Exslt.ExsltSets ">

<xsl:output method="xml" omit-xml-declaration="yes"/>

<xsl:param name="currentPage"/>
<xsl:variable name="menuNodes" select="$currentPage/ancestor-or-self::node[@nodeTypeAlias='RunwayHomepage']/node[./data[@alias='umbracoNaviHide'] = '0']" />

<xsl:template match="/">
<span style="white-space: pre;">  </span><ul>
<span style="white-space: pre;">      </span><xsl:for-each select="$menuNodes">
<span style="white-space: pre;">      </span> <xsl:variable name="currPos" select="position()" />
<span style="white-space: pre;">      </span> <xsl:variable name="classValue">
<span style="white-space: pre;">          </span> <xsl:if test="position() = 1">first </xsl:if>
<span style="white-space: pre;">          </span> <xsl:if test="position() = last()">last </xsl:if>
<span style="white-space: pre;">          </span> <xsl:if test="$currentPage/@id = ./@id">selected</xsl:if>
<span style="white-space: pre;">          </span><!-- Next two lines implements befor and after selected item classes -->
<span style="white-space: pre;">          </span> <xsl:if test="$menuNodes[number($currPos)+1]/@id = $currentPage/@id">beforeSelected</xsl:if>
<span style="white-space: pre;">          </span> <xsl:if test="$menuNodes[number($currPos)-1]/@id = $currentPage/@id">afterSelected</xsl:if>
<span style="white-space: pre;">      </span> </xsl:variable>
<span style="white-space: pre;">      </span> <li>
<span style="white-space: pre;">              </span><xsl:if test="string-length($classValue) &gt; 0">
<span style="white-space: pre;">                  </span><xsl:attribute name="class"><xsl:value-of select="$classValue" /></xsl:attribute>
<span style="white-space: pre;">              </span></xsl:if>
<span style="white-space: pre;">              </span><a href="{umbraco.library:NiceUrl(@id)}">
<span style="white-space: pre;">                  </span><xsl:value-of select="$classValue" /> : <xsl:value-of select="@nodeName" />
<span style="white-space: pre;">              </span>
<span style="white-space: pre;">          </span></li>
<span style="white-space: pre;">      </span></xsl:for-each>
<span style="white-space: pre;">  </span></ul>
</xsl:template>
</xsl:stylesheet>

Regards
.Hauge

Once again burned by the editor in this forum

Seems only way to get code properly into the forum is if you type it in by hand:

Short version:

To add before and after classe youll need three more lines of xsl in the classValue variable:

Outside the classValue variable You'll need a variable that stores the current position.

<xsl:variable name="currPos" select="position()" />

Inside the classValue you'll need two more lines

<xsl:if test="$menuNodes[number($currPos)+1]/@id = $currentPage/@id">beforeSelected</xsl:if>
<xsl:if test="$menuNodes[number($currPos)-1]/@id = $currentPage/@id">afterSelected</xsl:if>

They basically look at the next or the previous node in $menuNodes and checks if next or previous node is the current page node.

Regards
.Hauge

Thanks Jamie for the answer, but as Jesper said I already had that covered :)

Now you both seem to be going out from the same navigation template am I right? E.g. the variable $menuNodes is used to iterate. Now the template I wa using (which is the one that came with the Runway navigation module) does not store the nodes in a variable, it just selects them directly in the for-each statement. Can I find the template you are basing your code on somewhere? Because when I try to "decode" some the first post by Jesper, I don't get into the for-each loop.

From what I can see in the post, this is declared prior to the for-each loop:

Hi Thomas

You're right; there is something missing: A variable right after the currentPage param, it looks like this:

<xsl:variable name="menuNodes"  select="$currentPage/ancestor-or-self::node[@nodeTypeAlias='RunwayHomepage']/node[./data[@alias='umbracoNaviHide'] = '0']" />

I actually tested the xslt from my first post on a runway site, drop me a mail on jesper {at} jm-net {dot} dk, and I'll send you the file.

.Hauge

Hurray, it works great! 

Now on to finding out why it won't include my own document types..

is working on a reply...