I had a small master page issue which I fixed quickly but which made me want to complain.
One of the great things about .NET is the great design time experience. Dropping designer support for nested master pages irked me, and there are some other quirks as well. In one case, I have a page using <div> and the "float" style attributes for layout. As soon as the divs are nested three deep or so the content no longer renders in the designer. It seems to be specifically related to the style as I will explain along with the next issue.
In my master page for the site I import a style sheet like so:
<
style type="text/css">@import url(kcstyle.css);</style>
Obviously this is a relative path. If you create sub-directories beneath your site obviously this won't work so I changed to an absolute path like so:
<
style type="text/css">@import url(/KlipschCorner/kcstyle.css);</style>
When the content renders in the designer now it does not show my styles for any pages regardless of directory. When I run the site however all pages look great regardless of directory. Now that the designer can't find the stylesheet, the content which did not render inside my <div> tags before is now visible in the designer. I would assume the designer is in some way using an IE component to render behind the scenes but this might not be the case. The answer seems likely to be the fact that the "ASP.net Development server" is not behaving in the same way that running the site via IIS would. The inconvienient part is that if you are using newer standards like <div style="float:left;"> for your layout, the designer view looks nothing like the fully rendered view.
Compare this view without style:

To this one when the site is actually ran:

The only difference is the stylesheet. Maybe I'm complaining about something petty here, but it seems that this type of thing is going to annoy a lot of people. Isn't part of the point of the designer that you don't have to run it to see what it looks like?