Occasionally Visual Studio (2003) changes the Html when you go to design mode. While it reformats it, it may also add certain closing tags. This can be counter-productive if you're doing certain techniques where you want the Html to be the way you initially made it. I've heard rumors that 2005 guarantees that your Html won't get altered.
I see this Html changing in two categories:
- Ways you can solve it by adding extra html, such as multiple nested tables
- Ways that Visual Studio is just wrong
The problem with the first is that any extra html you add must be transported over the wire and rendered on the client, so it slows performance. The only helpful technique I know to avoid needing that extra overhead is to make Visual Studio open in Html view by default. Goto: Tools > Options > Html Designer > General, and set the options to open in Html instead of Design view. Ideally your UI is refactored enough (with user controls, base pages, custom controls, possibly #includes, etc...) that the Html can be managed in Html view. I can then save my page, "peek" in design view to check the overall layout, disregarding any potential changes from Visual Studio.
In the second category, one (seemingly) blatant bug I came across in Visual Studio was when I had a custom control with custom attributes, and the attribute didn't have a value (kind of like "nowrap" - it only needs the attribute, not any associated value). Something like:
kept getting maligned to something like below when I went to design view. The attribute values got disjointed from the attributes:
However if I put the value-less attribute at the end, then I could toggle back and forth between Html and Design view:
I'm not sure what causes this - it could be something with the custom control, value-less attribute, affect from other attributes, or something else, but it solved that particular problem.