Please see attached FXML which has nested popups: MenuButton > CustomMenuItem > MenuButton

Click on MenuButton1 to open its menu.

Click on MenuButton2 to open its menu - you'll notice there are two problems:

Firstly, and most importantly, the MenuButton2 menu is dismissed as soon as you try to hover over it, rendering it unusable.

Secondly, the MenuButton2 menu is also dismissed if you hover over other items in the MenuButton1 menu. I would expect that the MenuButton2 menu would need a click to dismiss just as the MenuButton1 menu does.

In SB, we want to leverage MenuButtons popup in order to show CustomMenuItem with custom UI. For example, clicking a MenuButton in the Inspector to show an Effects or Paint editor. This custom UI sometimes contains controls with popups such as MenuButton or ChoiceBox and these bugs are currently blocking us.