This is not an issue, is more like a request.
Many of us, use firebug. If we could use it inside netbeans that would be really really nice. If that's not possible, I would recommend to allow us to see the source code, when we select an element using the "inspect" tool attached on the embedded webkit browser.
At me moment, we can see the CSS properties on some sort of UI interface and while that seems to be interesting in order to change properties without getting our "hands dirty", many of us actually prefer to have their hands on the code right away. ;) And, most important than this, we should consider that it's much more faster to read (and change) some lines of selected code, instead of a User Interface with some labels and values, and lines, and buttons.
Hope someone takes this into consideration.