Wrong tag attribute name proposals appear in CA Window for CSS styles inside <style></style> tag when:

1. There is at least one whitespace character is placed between opening and closing "style" tags
and
2. The CA is invoked when the cursor is pointed right after the opening tag (i.e. "<style type="text/css">| </style>", where "|"-char indicates the cursor position.

In such cases WTP suggests proposals for a tag attribute name insertion, as well as CSS proposals.

Probably it's WTP's issue, because:

1. WTP decides which kind of proposals are to be calculated at some cursor position.