We have initialized it in the beginning of the script.
Fix weynhamz/vim-plugin-minibufexpl#11. Requires 'QuitPre' event, only works after Vim version 7.3.544. Before Vim version 7.3.544 in which 'QuitPre' event was introduced, we use function 'QuitIfLastOpen' to quit Vim properly. One drawback of this method is that it does not know the differences between commands ':q' and ':bd', which means calling ':bd' will also quit the Vim. Since 7.3.544, we use 'QuitPre' event to stop MBE before the Quiting of Vim actually takes place, and the ':bd' has also been properly handled.
Commit c31e8a6 prevents MBE from being updated for any deleted normal buffer, because 'BufDelete' event is triggered before the deletion actually takes place, at which moment the previous 'IsBufferIgnored()' function will always return false which makes 'AutoUpdate()' never called. As our 's:BufList' is always keeping updated, it should be checked in 'IsBufferIgnored()' too. Previous condition check is mainly to prevent updating MBE on the deleting stage of a renamed beffer, but there is acctually no way of telling whether that buffer is going to be deleted or renamed at this moment. For a renamed buffer, later 'BufAdd' event will add it back after all, so we should update MBE whenever a buffer gets deleted.