Going through the upgrade exercise I mentioned in my previous post.
All good but my menu is now poked - all bunched up to the left. Still works but looks really munged!
Mr. Google to the rescue!
The reason is that:
"The value of the property determines how the menu control renders markup for the Menu control.
In ASP.NET 3.5 and earlier versions, the Menu control uses HTML table elements and inline styles to specify the appearance of the menu in a browser. In ASP.NET 4 and later versions, by default the Menu control uses HTML listitem elements and cascading style sheet (CSS) styles."