Why the window File FileBrowserComponent does not open in a plugin?

Audio Plugins
1

Hello,
i have a plugin. I use it in Ardour7.5.
I would like a FileSelector. I write:

button->onClick = [this] { p->Process_message(); }; // callback
...
...
void P::Process_message()
{
 chooser.launchAsync(FileBrowserComponent::openMode | FileBrowserComponent::canSelectFiles, [this](const FileChooser& chooser)
      { // this function is called from the  main thread, when user has selected a file or closed the file window
        File selectedFile = chooser.getResult(); // get selected file
        if (selectedFile.existsAsFile()) // check if the file exists
         {
          //... part 1
          }
        else
         {
             //... part 2
              cout << "No File selected." << std::endl;
         }
       });
}

When i use the plugin as a standalone application, it works well: a window to choose a file appears and when i close it, the program goes to part1 in the code above.

However when i use the plugin inside Ardour, no window appears and the program goes directly to part2 above. So it does not work.

Do you have any suggestion please? Thanks,
Frédéric.

2

I can precise that the problem is on linux ubuntu 22.04 with Ardour 7.5.
I have tested the same plugin on MacOs with Ardour 7.5, and this works fine (no problem, the file chooser window appears).