Fixed.

There are two bugs actually:

1. If you enter "1.0" (or any x.0) in a field whose value is supposed
to be an int/long/etc., you get an error.  Instead it's best that such
integer values be converted to ints (i.e., 1.0 -> 1).

2. If you turn the slider for integer values, it sends non-integral
double values (1.23 etc.).

I've updated our internal code.  Here are the two files I modified to
fix things.  Let me know if these work for you.

sim/util/Properties.java