I ran in to something strange today…

The ASP.Net 2.0 Menu control renders differently in a browser and in the W3 validator. Loading the page in a browser results in the usage of the correct attribute ‘vertical-align’ for the image which is used to indicate a menu has subitems. I checked this in IE and FireFox and both browsers rendered correct XHTML. When you copy the source of the rendered page and paste it in the validator-textbox at W3.org, it validates the XHTML. When you check the page directly by entering a URL, the menu renders using the non-correct attribute ‘valign’, causing my page to fail validation.  But the copied source passes validation!

I’ll investigate this strange behaviour and get back at you when I find something. If you know where this is comming from: drop me a line in the comments.