Running Debian 12 KDE Plasma, with JDK 21.0.2 and JavaFX 23-ea, if the main stage is maximized and a new stage (like an Alert) is shown, the main stage gets resized, but the window icons still show that the window is maximized. Also, the application starts centered at the screen, but then it is moved to 0,0.

Steps to reproduce:

- Run the attached test on Debian 12 KDE Plasma with JDK 21.0.2 and JavaFX 23-ea, the application shows up centred in the screen (as expected).
 See "1. Initial stage.png", that shows the window, when the application starts, at x: 320, y: 82, size 640x509

- Click on second icon to the top-right of the window (up-chevron), to maximise the application, the stage will take the whole screen, and the icon will change into a diamond (as expected).
See "2. Maximized stage.png", that shows the maximized application, at x: 0, y: 0, size 1280x756

- Click on the Test label, to show the alert. The dialog shows up, but the stage is resized back to its initial size (unexpected).
See "3. Shrunk stage.png", that shows the application, after an alert popup is triggered. Window is resized back again to 640x509

- Note also that the second button to the top-right of the window still shows a diamond icon, instead of the chevron icon (unexpected).
See "4. Wrong state.png", after closing the alert, it shows the wrong window icon as it still indicates that the window is maximized and can be restored.

This issue can be reproduced starting https://bugs.openjdk.org/browse/JDK-8260528, right before 21-ea+13 up until head, and also starting 17.0.10 (since that issue was backported to 17u).