When I ever have to reinstall firefox, that is the first extension that gets installed into my browser. Very, very useful. Does alot of other things too.

Yes, WebDeveloper is one of the must-haves for making / validating sites amongst these:

HTML-Tidy-Plugin

ColorZilla

because I still ... did not find ... what I was looking for:

My requirements:
a) open stylesheet in editor and see all colors in preview window (like in "style studio", but it is only display and no function to click on "class .head" and jump into sourcecode automatically)
b) color wheel with complementary colors (like "color schemer" or "colorimpact")
c) a tool that can do both a) and b) -> "Eierlegende-Wollmilchsau"

My Questions:
1. firefox webdeveloper extension:
-> open style.css and select in menu:
-> Tools -> Webdeveloper -> ????????
-> how do I get Webdeveloper ...
-> to show colors of my stylesheet?
-> I installed colorzilla and html validator -> but how ..
2. Is there any "Eierlegende-Wollmilchsau" (thats a bavarian type of Wolpertinger that does everything like eggs, wool, milk, meat ...)? How about Zend, Dreamweaver ...

Hello Hans et al.

I am a big fan of TopStyle for editting stylesheets.

You can see more at: http://www.bradsoft.com/topstyle/index.asp