plugin and context and privileges...

Hello,

Right before calling a plugin from my FF add-on JavaScript, I can access and retrieve window.Components.stack. However, once inside the plugin I just called, the stack attribute is no longer accessible.
I can retrieve window.Components without any problem but the stack member is gone!
After some experiments, we've noticed that this seems to be related to how this whole code path started (e.g. click XUL element vs. ~programatically).

Do you have any idea why that privilege to access the stack would be remove like this?