Left menu in properties dialog is able to be resized now.

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)