Draft PR for JDK-8233678: [macos 10.15] System menu bar does not work initially on macOS Catalina

[Kevin Rushforth]

I have created a Draft PR for JDK-8233678 (System menu bar does not work 
initially on macOS Catalina) here:

https://github.com/openjdk/jfx/pull/361
It's just about ready for formal review, once I remove the debugs print 
statements, but before I do I'd like someone other than me to validate 
this on a macOS 10.15 (Catalina) or macOS 11 (Big Sur) system. If anyone 
does try it, go ahead and add a comment to the PR.

Thanks.

-- Kevin