Issues when using WebGL in an extension

I have written an extension based on the idea of using Photoshop to edit textures live on a 3D model.

In my extension I open a Collada model using the three.js framework.

i can take the document in focus, save a merged copy and load it as a texture on the model.

When using Canvas renderer this works every time, although ofcourse rendering is painfully slow.

Using the WebGL renderer the extension sometimes works, and sometimes crashes when updating

the texture. I have tried every method possible in three,js, (changing texture, creating new material, updating map explicitly, etc, etc)

with the same result. All ways work in Canvas, and only occasionally in WebGL.

It is incredibly hard to debug, as the javascript debugger dies along with the extension window,

Any help, suggestions very gratefully accepted

Cheers!