I figured out this neat trick quite by accident, but it's great! If you press the Ctrl button and scroll with the mouse wheel, you can control the size of the chat box and other elements of your user interface! You can keep it at 100% or make it bigger to see the chat box, the cell phone, and the building tools better.
Here's the UI (user interface) with the setting at 150%:
And here it is at 75%:
Very cool and very useful!