Our Swing application uses InfoNode Docking Windows (http://infonode.net/index.html?idw) to enable such fancy stuff like - you know - docking windows. The problem here was that any action related to this docking framework (undocking, docking, minimizing and so on) caused the application to shutdown. That was the case with the first beta release.
Yesterday I downloaded and tested beta b30 and it's better now. But there are still problems. As long as I don't use any docking window action I have a running WebView (in a JFXPanel) inside such a docking window. But as soon as I want to undock or minimize and maximize it, the JFXPanel doesn't display anything. I think it's an JFXPanel issue since I tried it again with an empty JFXPanel. After undocking the JFXPanel, the border was gone.

I really tried to resolve this problem in long debug sessions. But I didn't get it. I'm not even sure if it's a JavaFX problem or a problem caused by the docking window framework. But I hope that you can find the cause of this issue.

I've attached an example application to this issue. Additionally you need the docking framework. It's a single jar available at Sourceforge (http://sourceforge.net/projects/infonode/files/InfoNode%20Docking%20Windows/). I tried the latest version of this framework.