MacVim, NerdTree, Janus Annoyances

I've decided to use Vim for a few weeks at least and am enjoying it. There are plenty of posts on using Vim as a Ruby IDE and switching from your IDE of choice. Most of the TextMate to Vim posts seem to recommend Janus and for good reason.

Janus adds a number of plugins and settings to Macvim including NerdTree. NerdTree displays a project drawer in a window which is in a vertical split, normally alomgside your working buffer. The first problem is that if you close your working buffer with :bd or :bw, the NerdTree window will fill the MacVim tab, to cycle to the next or previous buffer then entails resizing splits which is not what I want.

Janus solves this with a function in .vimrc:

This function closes the MacVim tab (i.e. Cmd + W) if there is only one tab and it contains 2 windows, one of them with the NerdTree buffer. Unfortunately this doesn't consider buffers that are not currently displayed. If I want to close MacVim or the MacVim current tab, I'll use Cmd + Q or W, when I delete a buffer I want the window to display the next buffer.

To disable the Janus function add an override to .vimrc.local:

It's better to make changes in .vimrc.local and .gvimrc.local as Janus can be updated to the latest version without losing your customisations.

Luckily there is a script on the vim wiki that keeps the window open when deleting a buffer. It can be amended to ignore the NerdTree buffer, if I want to close NerdTree I will use the key mapped to toggle it:

I would like to map :bd to :Kwbd but it seems it can't be done (I'd be happy to be proved wrong here) so have mapped Ctrl + Shift + B in .vimrc.local: