I wrote a Quick&Dirty gamepack without reading any documentation, I probably made many mistakes and there is still Doom 3 references in that game pack, by the way, all the things you will see in screenshots below were obtained without writing and compiling any custom DarkRadiant code. There is no need to hardcode game support like you have to do with GtkRadiant 1.6. Just put the game file in the right folder to add your own game supported, the same way you would do with NetRadiant.
They ported the GUI from GTK to WxWidgets, it works as well on Linux and that other OS named Windows. It also means it runs on Mac OS with a native Cocoa interface without needing XQuartz at all. In fact, I had some talks with @cu-kai trying first to compile GtkRadiant and NetRadiant on his Mac, then DarkRadiant. I copy/paste there some quotes from the talk:
<illwieckz> I don't know how well done the mac support is
<cu-kai> lol yeah i just noticed
<cu-kai> no build instructions for mac os
<illwieckz> there is no mac reference on their website
<cu-kai> this is too easy
<cu-kai> something will go wrong
<cu-kai> it works
<cu-kai> shit, it works
Yes, it works, and there is an extra candy for you: the pk3dir support is already in and it works too, that's something that is not yet merged in both GtkRadiant and NetRadiant but is there since years in DarkRadiant.
Here, you see a preview of the Metro map, the map and its textures sit in map-metro_src.pk3dir, while the ads textures sit in tex-metro-ads_src.pk3dir. Everything load. There is some issues with some textures, not all of them, sometime they are not correctly scaled, I guess it's a minor issue that would not be hard to fix. As you see, there is a texture browser (not like in GtkRadiant 1.6).
There is native md5 model support (I wonder if it would be easy to merge iqm model support from aaradiant). This is how looks md5 models in DarkRadiant. There is also an md5 animation preview interface, but I haven't figured out yet how to get a model in it.
This is how you add map models with DarkRadiant (right click on orthogonal view, “Create model…”).
There is a built-in particle editor but I haven't figured out yet how to use it and if it's usable for idTech 3 related stuff.
I said there is a texture scaling issue. I hope it's minor and easy to fix. This is how look the Boil and Dark Zone maps for the upcoming Xonotic 0.8.2 release. Boil's textures look OK, Dark Zone's not.
We can see similar things with Unvanquished maps. As seen on the screnshot of Metro map above, some look OK, some not. On this Parpax screenshot, the textures are obviously not correctly scalled. Same problem with the Forlorn map, but you still recognize the map easily, and you can notice updates are coming in Forlorn!
Not only textures has issues, some models are not correctly scaled too: some are ok, some are not, as you can obviously notice it on these Vega screenshots. Do not be fooled by that vehicule, it's a matter of point of view, it's obviously wrong !
DarkRadiant does not ship any map compiler since id Tech 4 features a built-in map compiler, but we can just use q3map2 from netradiant for that task.
This is very promising and at first glances there is only minor issues to fix. If we need to merge something, the gap between NetRadiant and DarkRadiant looks to be far far far smaller than the one between NetRadiant and GtkRadiant 1.6. Also, DarkRadiant is well maintained, probably more maintained than GtkRadiant, enough to get packaged in Debian and Ubuntu ! That's impressive ! On the features, it looks like GtkRadiant < NetRadiant < DarkRadiant. I don't know yes what is missing from NetRadiant but I hope it would not be too hard to merge them in DarkRadiant. That looks very promising!
The DarkRadiant souce code is hosted on GitHub and bug tracked sits in The Dark Mod bug tracker.
Thing you need to know: It just loads the map with quake3 format, currently I haven't managed to save it as quake3 one. It looks like to be an issue in DarkRadiant itself, perhaps it's not wired correctly or it's just my quick&dirty gamepack that is malformed. So, if you want to try out, only test on copied files, do not overwrite your precious maps!!!! Edit: it looks like it's even not the doom3 format I got when I write quake3 maps in DarkRadiant, probably bugs somewhere…