Seems to be there's an issue with Fan and JS not agreeing on how to handle nulls, not surprising, I'm guessing we're gonna need a lot of test cases for nullable types.

The code that brought this up looks like:

class Cell : Canvas 
{
  Int? highlighted  // unitialized until mouseover

  //in onPaint
    for (d:=0; d<9; d++) {
      if (d == highlighted)  // yielding true when d == 0

Promoted to ticket #750 and assigned to andy

Good catch Kevin - yeah I need to get the full test suite up and running. Its a bit bolted on right now.

Ticket resolved in 1.0.49

Should work now.