Left menu in properties dialog now able to be resized.

Left menu couldn't be resized, so user wasn't able to see full label. Now when whole window resizes, menu resizes too. (See screenshots).
![before](https://cloud.githubusercontent.com/assets/1764869/4739462/db1f622c-5a04-11e4-899f-35c2877fa2a9.png)
![after](https://cloud.githubusercontent.com/assets/1764869/4739461/db19fa94-5a04-11e4-8072-88e2d40ed830.png)