Stage Manager Problems

[Jeremy Wood]

We’re experiencing problems related JFrames while Stage Manager 
<https://www.computerworld.com/article/3667999/what-is-apple-stage-manager-and-how-is-it-used.html> 
is active Mac.

When Stage Manager is active the yellow minimize button on our JFrame’s 
appears to “minimize” our app. But as far as our Frame is concerned:
1. Frame.getExtendedState() does not indicate we’re in an ICONIFIED 
state
2. Frame.isShowing() returns true
3. a java.awt.desktop.AppForegroundListener believes our app is in the 
foreground.

We want to identify when we’re in this hidden state. Is there any other 
property we can consult to help identify this state?

I’m happy to submit an openjdk ticket if needed, but first I wanted to 
sanity check that I’m not missing something. (I also tried querying 
<https://bugs.openjdk.org/issues/?jql=text%20~%20%22%5C%22Stage%20Manager%5C%22%22> 
the openJDK bug database, but didn’t see any hits.)

I tried rummaging around in Mac-specific classes (like CPlatformWindow), 
but I didn’t see any promising leads. It’s always possible I missed 
something, though.

Attached is a small 200-line demo app.<<attachment: StageManagerTest.java.zip>>