Not a bug, but rather more of a WebGL limitation - you can read about it in this post.
What it all boils down to is that WebGL doesn't support rendering text, so to get around this, the rendering engine draws all text to an HTML5 canvas above the WebGL window. An unfortunate limit of the technology right now.
Well it's not a limitation of the technology exactly. AFAIK WebGL can render texts it's just not built-in since WebGL is just an implementation of low level graphics api OpenGL ES 2.0 for web. It's just the way Ash implemented texts that it's not compatible with WebGL.Kiyoshi2012-01-24 22:27:48