[ChoiceBox] List doesn't show up on initial press of ChoiceBox

Steps to reproduce

1. Run Ensemble8
2. Click on the "Stacked Area Chart" demo in the upper center of the initial screen
3. In the "Playground" section, scroll down until the "side" ChoiceBox is visible (default value = "LEFT")
4. Click on the ChoiceBox

The expected behavior is that a list with "TOP", "BOTTOM", "LEFT", and "RIGHT" is shown. However, the first time, only a small white rectangle is shown. On the second and subsequent times it works.

If you scroll down to the other choice boxes -- "legendSide" and "titleSide", the same behavior occurs. The first time each of these is selected, the list is rendered as a small rectangle; second and subsequent times it works fine.

The "ChoiceBox" demo also shows this bug.