use a different method to get a controller

https://github.com/BlackFoundryCom/Power-Ruler/blob/14e428924e75b25785722096ad39104aad363de3/PowerRuler.roboFontExt/lib/PowerRuler.py#L55

the easiest is to at a custom variable to NSApp()

```python
from AppKit import NSApp

NSApp().myCustomController = "foo"
```
