[BUG] Window decorations missing on GNOME 46 Wayland (Fedora 40 Silverblue)

[ghost]

Describe the bug When creating a QMainWindow, decorations such as the [_][ ][ X ] are missing from the window, even after setting the flags.

To Reproduce Steps to reproduce the behavior:

1. Call QApplication.initialize(...) with empty arguments.
2. Create a QMainWindow instance, call these flags:

   Qt.WindowType.Window
   Qt.WindowType.WindowMinMaxButtonsHint
   Qt.WindowType.WindowCloseButtonHint

3. Run the application by calling QApplication.exec

Expected behavior I should have my three decoration buttons.

Screenshots

System (please complete the following information):

• OS: Fedora Linux 40.20240713.0 (Silverblue)
• Java version: 21.0.3
• QtJambi version: 5.15.20
  • Qt version: 5.15.14

Additional context MyWindow.scala

object MyWindow extends QMainWindow:
  this.setBaseSize(640, 480)

  this.setWindowTitle("Example")
  this.setWindowFlags(
    Qt.WindowType.Window,
    Qt.WindowType.WindowMinMaxButtonsHint,
    Qt.WindowType.WindowCloseButtonHint
  )

Main.scala

object Main extends App:
  QApplication.initialize(Array.empty)

  val window = MyWindow
  window.show

  QApplication.exec
end Main

build.sbt

// ...
libraryDependencies ++= {
  val qtjambiVersion = "5.15.20"

  Seq(
    "io.qtjambi" % "qtjambi" % qtjambiVersion,
    "io.qtjambi" % "qtjambi-native-linux-x64" % qtjambiVersion
    // "io.qtjambi" % "qtjambi-native-macos" % qtjambiVersion,
    // "io.qtjambi" % "qtjambi-native-windows-arm64" % qtjambiVersion,
    // "io.qtjambi" % "qtjambi-native-windows-x64" % qtjambiVersion
  )
}

[omix]

I am not able to reproduce this behavior. However I tried it Java not Scala, on Ubuntu not Fedora, with Qt 5.15.13 not 5.15.14. This is most likely not a QtJambi bug. Either it is a matter of addressing the methods from Scala or of Qt on your system. What happens if you start the application with argument -platform xcb?

[ghost]

I am not able to reproduce this behavior. However I tried it Java not Scala, on Ubuntu not Fedora, with Qt 5.15.13 not 5.15.14. This is most likely not a QtJambi bug. Either it is a matter of addressing the methods from Scala or of Qt on your system. What happens if you start the application with argument -platform xcb?

It seems that -platform xcb solves the problem with the decorations.

I don't think you'd be able to reproduce this issue if you deliberately choose not to use identical configuration to set it up, like using Scala over Java (despite being JVM) oder a RedHat-based distribution of Linux.

EDIT: You do however lose out on HiDPI scaling, so now you'd have to deliberately resize the window twice to get the exact same resolution you'd get if it was properly scaled. Perhaps this ist a bug with GNOME Wayland on certain distributions, oder a bug with Qt itself?

[omix]

I am not able to reproduce this behavior. However I tried it Java not Scala, on Ubuntu not Fedora, with Qt 5.15.13 not 5.15.14. This is most likely not a QtJambi bug. Either it is a matter of addressing the methods from Scala or of Qt on your system. What happens if you start the application with argument -platform xcb?

It seems that -platform xcb solves the problem with the decorations.

I don't think you'd be able to reproduce this issue if you deliberately choose not to use identical configuration to set it up, like using Scala over Java (despite being JVM) oder a RedHat-based distribution of Linux.

Yes I agree. However I don't have you configuration available on the fly. Since Xcb behaves as expected I think it's something between Qt and Wayland or specific to Fedora. I suggest to search specific Qt forums for this issue.

In general, you don't need to set window flags at all to let min/max/close appear. It shows up by default.

[ghost]

I am not able to reproduce this behavior. However I tried it Java not Scala, on Ubuntu not Fedora, with Qt 5.15.13 not 5.15.14. This is most likely not a QtJambi bug. Either it is a matter of addressing the methods from Scala or of Qt on your system. What happens if you start the application with argument -platform xcb?

It seems that -platform xcb solves the problem with the decorations. I don't think you'd be able to reproduce this issue if you deliberately choose not to use identical configuration to set it up, like using Scala over Java (despite being JVM) oder a RedHat-based distribution of Linux.

Yes I agree. However I don't have you configuration available on the fly. Since Xcb behaves as expected I think it's something between Qt and Wayland or specific to Fedora. I suggest to search specific Qt forums for this issue.

In general, you don't need to set window flags at all to let min/max/close appear. It shows up by default.

I think for now, the issue ist solved. I shall go ask the Qt community around if they know anything about this issue because now it'st definitely an issue with Qt und GNOME (oder Fedora too) und not this library.