Well, Visual Studio .NET is probably the best IDE I've seen in ages. It even kicks IDEA's butt, IMHO. My question is, how hard would it be to reproduce it's look and feel?
Have you heard of SharpDevelop? It's a GPL'd VS.NET knock-off, although I'm sure they add in some goodies of their own too.
SharpDevelop is fairly nice, but is a complete resource hog. Orders of magnitude more so than VS.NET.
Some GUI libraries make it a point to reproduce every GUI trick used by Microsoft. For example, CodeJock (http://www.codejock.com) comes with a sample program that duplicates the entire VS.NET IDE (just its look, of course). I tried it about a year ago and it was nicely written, but I decided not to use it in the end.
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