First of all, congratulations (to Nicolas and Volker) on the tool, this is a big step for Horde

The GUI looks quite professional, and I can't wait to start using it!
However, I'm having quite a few problems in getting it to work with the standard Horde content (the content that comes with the Horde engine, not the content that comes with the editor).
On my hard-drive, I have everything that comes in "\Horde3D SDK [0.11.1]\Samples" extracted to "C:\Programming\bin".
In the editor, I've changed all the content paths to match this location in File->Settings (e.g. Scene Graphs is set to "C:/Programming/bin/content/models").
When I try to open the file "C:/Programming/bin/content/models/knight.scene.xml", I get an Error box which says "Error initializing Pipeline".
After this error happens, if I go into the Scene->Pipeline dialog and try to open "C:\Programming\bin\pipeline.xml", then I get an error box that says "Error opening existing pipeline file: C:/Program Files/HordeEditor/bin\Pipelines\".
I can make this error go away by copying a pipeline.xml file into that folder, but this is only a work-around... I want it to load the pipeline files from "C:/Programming/bin".
After I've used the above work-around, and tried to load "knight.scene.xml" again, I get another error which says "Error when opening file C:/Programming/bin/content/models/models! No such file or directory"
I don't know what to do about this error...
Apart from that, I think the plug-in feature is great, but I'm concerned about the license mis-match with the Horde engine. For example, if a professional game company uses Horde3D, they can integrate it with their proprietary game-engine, but they cannot integrate their game engine with the editor using plug-ins - because the plug-ins must be GPL.
I think it would be a good idea to license the plug-in API using the same license as the horde engine (but the rest of the editor should stay as GPL).