The Create New Terrain tab within the Terrain Toolbox allows for infinity Terrain Width, Height, or Depth. This will allow the user to create a new Terrain Object with these values set, which causes thousands of Exceptions to be thrown and cause significant lag within the Editor until the new Terrain object is deleted.

Repro Steps:
1. Install Terrain Tools 4.0.0-pre.1
2. Open up the Terrain Tools window
3. Select the Create New Terrain Tab
4. Set Total Terrain Width, Length, and Height to infinity
5. Click Create

Actual Results:
New Terrain object is created with infinity values and many exception's will occur.

Expected Results:
Infinity would not be allowed as an input for Create New Terrain