As we all know, when a user double-clicks on a window title bar, that window gets resized to the full available screen size. At least I have seen this happening in Mac OS. Any idea how to capture this event? What should I listen to in my code so that I know that the user has single or double-clicked the Window title?
2 Answers
Don’t try to intercept interactions with Window decorations directly
Don’t try to work with clicks. Handling state changes due to keyboard or window decoration interactions differs between OSes and isn’t a JavaFX function anyway.
Use Stage properties and API instead
Stage has a maximized property (and iconifed), listen for changes on relevant properties. Similarly, there is a full screen mode which is a bit different (see Stage Java doc).
Creating your own window decorations
If you really want complete control, you can use an undecorated stage style and add your own decorations in JavaFX for handling basic window system functions. That way, a lot of the decoration functionality can be handled internally by your app, but I really don’t recommend that. There was an old project named Undecorator which assisted doing this if you wanted to go that route (I don’t advise coding it yourself).
Capturing clicks is a bad idea as @jewelsea mentioned in his comment. The effort in the question was to know why the behavior. Upon research, I found that it is a bug already listed by Oracle - please find below: Each window when double-clicked on the title bar is expected to assume full-screen height and width (Maximised) and on double-clicking title bar again should get back to its previous size. This is not working beyond JDK8 is what I understood from this link. However, on macOS Monterey 12.1 (OpenJDK 17) the window is assuming maximized size on double-clicking the title bar, but, is unable to go back to the previous size when double-clicking again.
https://bugs.java.com/bugdatabase/view_bug.do?bug_id=JDK-8232812
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