Using Vim’s tabs like buffers

Stop, stop, stop.

This is not how Vim’s tabs are designed to be used. In fact, they’re misnamed. A better name would be “viewport” or “layout”, because that’s what a tab is—it’s a different layout of windows of all of your existing buffers.

Trying to beat Vim into 1 tab == 1 buffer is an exercise in futility. Vim doesn’t know or care and it will not respect it on all commands—in particular, anything that uses the quickfix buffer (:make, :grep, and :helpgrep are the ones that spring to mind) will happily ignore tabs and there’s nothing you can do to stop that.

Instead:

• :set hidden
  If you don’t have this set already, then do so. It makes vim work like every other multiple-file editor on the planet. You can have edited buffers that aren’t visible in a window somewhere.
• Use :bn, :bp, :b #, :b name, and ctrl-6 to switch between buffers. I like ctrl-6 myself (alone it switches to the previously used buffer, or #ctrl-6 switches to buffer number #).
• Use :ls to list buffers, or a plugin like MiniBufExpl or BufExplorer.