wycats's "disallow insert mode"
An explanation from vguerci@github:
Insert mode can be entered in nerdtree not sure the exact sequence / reason, but i guess that involve using mouse (sounds weird, a bug?) :
- open nerdtree, select a buffer, enter insert mode in buffer.
- select nerdtree buffer with mouse, you're in insert mode.
...then you can easily get E21, E382 errors.
Not a big deal but that can happen, if you use mouse... (which I don't)
(reproduced this on latests macvim (vim 7.3.260) from terminal (vim) or macvim)