I keep getting this error:

```
TypeError: Error #1006: setSize is not a function.
    at circles::SpiroUI/doSliders()[/Users/wakemana/Documents/Adobe Flash Builder 4/SpiroPaint/src/circles/SpiroUI.as:74]
    at circles::SpiroUI()[/Users/wakemana/Documents/Adobe Flash Builder 4/SpiroPaint/src/circles/SpiroUI.as:42]
    at circles::Spirograph()[/Users/wakemana/Documents/Adobe Flash Builder 4/SpiroPaint/src/circles/Spirograph.as:115]
    at circles_fla::MainTimeline/frame1()[circles_fla.MainTimeline::frame1:2]

```

I have included import `fl.controls.*` and `fl.events.*` and I've also made sure the Slider UI component is included in the Document library.

The UI keeps flickering in a strange way, seems to be redrawing the components in every frame or something. I did have this all working before, but since introducing some new classes, it's stopped working. The rest of the drawing within the application is working, just the UI components flicker and don't work.

Help appreciated :)