If the client, maintaining the site, just adds new documents to the tree, Wayfinder automatically would reflect these changes. So I come back to a solution with Wayfinder instead of Ditto.
By default, WF uses unordered lists for the output. So in the templates for the submenu if you replace the <ul><li>-structure by <span>, you will get the submenu items in a row with the main menu items. (For the main menu we keep the <ul> list but give the <li> items the format display:inline.)
In detail:
WF-call:
[!Wayfinder? &startId=`0` &level=`2` &rowTpl=`myRowTpl` &innerTpl=`myInnerTpl` &innerRowTpl=`myInnerRowTpl` !]
Chunk myRowTpl:
<li style="display: inline;" [+wf.classes+]>
<a href="[+wf.link+]">[+wf.linktext+]</a>[+wf.wrapper+]
</li>
Chunk myInnerTpl:
<span [+wf.classes+]>[+wf.wrapper+]<span>
Chunk myInnerRowTpl:
<span [+wf.classes+]>
<a href="[+wf.link+]">[+wf.linktext+]</a>[+wf.wrapper+]
</span>
That should do it. For the documents you don’t want to see in the menu just uncheck the "show in menu" option. Because the order you want is the same like in the documents tree, WF will order automatcally in the right way.
With this solution it will be no problem for the client to maintain the site.
All the best for your project!
ottogal