Sorry, I didn't finish the post.

I found that eventually the sliderChangeListener makes this call

  sliding = true;
  setValue(newValue("" + d));
  sliding = false;

On my system since d was a double it creates a decimal string. Eventually
this  goes to Properties.setValue() where it tries to parse the string as as
an integer. When it does this I get a NumberFormatException.

Incidentally, I get the same exception when I type a decimal (or any non
integer) into the text field for the property inspector.

I fixed the slider problem by casting the "d" variable to integer before the
string concatenation if the domain isn't a double. I haven't yet fixed the
exception when the number gets typed in.

Is this a bug or am I doing something wrong?