Qt comes the closest, and it has all sorts of platform-specific hacks in it, some even visible at the API level.
If you're going to be writing something that's used as frequently and intensively as an IDE, then it had BETTER conform to the user interface guidelines of whatever OS it's running on. Those differ on Windows or Mac, and Linux doesn't really have any.
But GNOME definitely has them[1], and newer projects which have dedicated themselves to a really solid HIG are gaining a lot of traction[2].
[1] http://developer.gnome.org/hig-book/stable/ [2] http://elementaryos.org/docs/human-interface-guidelines
I guess the issue comes down to more people needing to _care_ about them :)
IDEs are mostly just big rectangles full of text, which are eminently platform independant. Developers are special in that that we are very used to staring at terminals and logs, and are very accustomed to work with colored but unformatted text. Also, workflows tend to be very similar, across platforms and environments.
So that leaves us with not much reason for platform dependance, and thus Eclipse, Emacs/Vim/etc., and terminals. Even Visual Studio sports many things, but a native look is not among them. I guess XCode is the only really platform-dependant IDE I know. All the others could just as well run on different platforms or even do so.
So, umm, I respectfully disagree.
PyDev seems to heavy to me when you need to write a standalone script and too buggy at evaluating module dependencies resulting in bad tooltips. Ipython notebook doesn't have this problem because you evaluate code as you develop, so tooltips come from object introspection.
It works out of the box and also supports javascript/html/css/... so is ideal for developing webapps with a python backend.
Ninja looks nice, but nothing I saw in the screencast makes me want to make the jump.
There is a big difference with PyDev/Aptana that is not apparent in the screencast: its lightweightness!
* it is a 1.3Mb download (vs 126Mb).
* startup time is ~2s (vs 30+ seconds)
* memory footprint is ~28Mb after startup (vs 400Mb)
Now I'll definitely try it.
Update: the memory quickly jumped to ~120Mb usage, hope it's not a memory leak.
I hope the group who agrees with me is cancelling out all the down-votes I got for expressing a valid & common opinion. :)
Many users do value a good cross-platform application.