Resolution Issue with Multiple Chalktalk Clients

Tested in branch v2.0, two clients in two different machines behaved differently. These two different machines have different screen resolutions.

![client1](https://user-images.githubusercontent.com/10137769/55827513-5a8aea80-5ad8-11e9-8634-cd8569de3ede.png)
![client2](https://user-images.githubusercontent.com/10137769/55827517-5d85db00-5ad8-11e9-93b4-1948dc4c4d9b.png)

