mintty, tmux causes vim to go bonkers.

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Open a mintty session
3. start tmux
4. open up a file in vim

What is the expected output? What do you see instead?

I'd hope vim would show up just fine. :)  Instead, I basically see vim smushed 
into one-to-two lines, and scrolling is messed up.  This messes up other 
console programs on the remote like ncdu and the like as well.

What versions of mintty, Cygwin/MSYS, and Windows are you using?

mintty: 1.2-beta1 (x86_64-pc-cygwin)
cygwin: 1.7.35(0.287/5/3)
Windows: Windows 8.1

Miscellaneous version info:
tmux: 1.9a

Please provide any additional information below.

I've noticed that this problem goes away if:

- I don't use mintty, and instead use command prompt. (this makes me sad.  I 
love mintty!)

- I don't use tmux, but use mintty.

It doesn't matter if I have a valid tmux.conf or it's empty, this still occurs.

Original issue reported on code.google.com by ed...@kickingdragon.com on 2 Apr 2015 at 6:34

[GoogleCodeExporter]

Cannot reproduce. It looks fine here.

Original comment by towom...@googlemail.com on 6 May 2015 at 8:34