code reformatting? How to avoid?

why do some wysiwigs add to and reformat code?

[benlieb]

I use dreamweaver a lot, usually in code layout, but every now and then it's helpful to use the wysiwyg to add or change text.

Dreamweaver doesn't reformat my php files with html tags and meta tags because it thinks I forgot them. But other OPEN SOURCE wysiwygs do.

Why do all open source wysiwygs seem to do this and what can be done to stop it or avoid it?