These dictionary keys are supposed to be integers, not strings.  See their definition near the beginning of the module.  The real problem is that `self._coloursMap` has not been initialized, and that is happening because of another exception that is being triggered by the test that you should already  be familiar with:

```
    img = wx.Bitmap(xpm)
TypeError: Expected a list of bytes objects.
```

So please change all these string keys back to the integer variables, fix the XPMs in fmresources.py to be bytes instead  of strings, and test again.