Well, I’ve always felt a bit unhandy to see endless responses within the Fiddler inspector window without the chance to collapse nodes or have a basic color syntax, so I used to copy and paste text from fiddler to Notepad2 (love it too!).
Some time ago I stumpled upon a control on Codeproject that caught my attention: FastColoredTextBox. Putting all together has been a really trivial task, I’ve just changed some lines of code here and there, however I’ve to say that the resulting prototype is quite pretty.
By the moment I’m sharing the code in a Zip on my SkyDrive, but if someone else is willing to try the project there is room for several improvements, like a proper folding, searching within the inspector and so on.