We are working on a standalone Bullet Physics Editor, currently for Windows and Mac. It is still early in development, and it doesn't have proper editing features yet.
Currently the editor can
load/save files in the .bullet file format, created using the Bullet 2.76 or later SDK or Dynamica Maya plugin.
select translate, rotate objects, delete objects
view some properties such as position, mass, collision shape type
play/pause the simulation
toggle between 1 and 4 split views using space bar, similar to Maya controls
We are experimenting with several GUI library options. Currently we use Cocoa/Objective-C for the Mac OSX GUI, and .net/C# for Windows GUI. For the future we explore wxWidgets for Linux (and if we are very happy with that we might drop the native Cocoa/.Net implementations)
If the editor was based on wxWidgets, it would be much more easy to mantain the several platforms (Win, Mac, Linux), and it have many great controls, like a property editor and OpenGL panel, and much more!
Regarding the Bullet Physics Editor, is there any library I must install before running the windows version?
If those crashes and incompatibilities persist, we might migrate to wxWidgets.
A related project, OgreKit/GameKit, uses wxWidgets and OpenGL for a node editor. It builds on Windows and Linux using the cmake build system, we still need to fix Mac OSX cmake support. See http://code.google.com/p/gamekit/downloads/list