Auto pseudo site tool - verification of key strokes

[jdduh]

The field validation should occur when the user clicks on the "Find Site" button. The current implementation makes it difficult to move from one field to another without entering a valid value (e.g., when the user wants to abandon an operation). Also, the current implementation won't treat ".1" as a valid value.

[lbross]

This is done for elev, precip, and a single proximity layer. It will need to be updated when adding multiple proximity and/or location layers.