nerdtree textwidth in new windows

Question

I'm using macvim with the janus plugin that includes nerdtree with it.

The issue that I am having is that whenever I open a file using 'o' from the nerdtree file browser, for some reason it resets the textwidth to 79 in the new buffer that the file is opened into.

I can override this back to 0 in the new buffer and vim will behave correctly, but whenever I switch files, the textwidth gets set back to 79.

I have textwidth set to 0 in my .vimrc file and this is correctly picked up by other files opened in vim, the file browser tab in nerdtree and even the initial empty buffer that is opened when I do 'mvim dir'. It's just when I use 'o' to open a file that this vim variable gets reset.

Does anyone know how to address this? I'm seeing the same behavior in gvim with the janus plugin as well.