Pandas to_csv unstable interaction with tkinter filedialog
#### Example

```python
from tkinter import filedialog
import pandas as pd
import numpy as np

data = pd.DataFrame(np.random.randn(13, 5))
outfilename = filedialog.asksaveasfile() #get save location

data.to_csv(outfilename, index=False, header=False, mode='a')
```
Gives an empty or unaltered file with no error messages. Full importation of tkinter and call as `tkinter.filedialog.asksaveasfile()` yields the same result.

#### Expected Output
However, if all references to tkiniter are removed:

```python
import pandas as pd
import numpy as np

data = pd.DataFrame(np.random.randn(13, 5))
outfilename = "C:\\test.txt"

data.to_csv(outfilename, index=False, header=False, mode='a')
```
then the file is written perfectly.

NOTE - if full tkinter or filedialog are imported but not used, then `to_csv` functions normally as well

```python
from tkinter import filedialog
import pandas as pd
import numpy as np

data = pd.DataFrame(np.random.randn(13, 5))
outfilename = "C:\\test.txt"

data.to_csv(outfilename, index=False, header=False, mode='a')
```
#### Output of ``pd.show_versions()``

<details>
INSTALLED VERSIONS
------------------
commit: None
python: 3.5.2.final.0
python-bits: 64
OS: Windows
OS-release: 10
machine: AMD64
processor: Intel64 Family 6 Model 42 Stepping 7, GenuineIntel
byteorder: little
LC_ALL: None
LANG: None

pandas: 0.18.1
nose: 1.3.7
pip: 8.1.2
setuptools: 23.0.0
Cython: 0.24
numpy: 1.11.1
scipy: 0.17.1
statsmodels: 0.6.1
xarray: None
IPython: 4.2.0
sphinx: 1.3.1
patsy: 0.4.1
dateutil: 2.5.3
pytz: 2016.4
blosc: None
bottleneck: 1.1.0
tables: 3.2.2
numexpr: 2.6.0
matplotlib: 1.5.1
openpyxl: 2.3.2
xlrd: 1.0.0
xlwt: 1.1.2
xlsxwriter: 0.9.2
lxml: 3.6.0
bs4: 4.4.1
html5lib: None
httplib2: None
apiclient: None
sqlalchemy: 1.0.13
pymysql: None
psycopg2: None
jinja2: 2.8
boto: 2.40.0
pandas_datareader: None

</details>
