QWidget-Method hide() destroys surface in IVI-enabled Wayland-Compositor

Question

I have a compositor based on the IVI compositor example in which I can manipulate visibility of surfaces via the "visible" property of the respective surface.

However, when a client tries to hide a QWidget via the hide() method, the compositor will destroy the surface instead of just setting the visible property to false. Is this the intended behavior, and if so, is there a way to change that?

Steps to reproduce:

• Build and run the compositor example
• Create a new Qt Widgets Project in QtCreator, leave all settings at default
• Change mainwindow.h and mainwindow.cpp to look like this:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QTimer>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private:
    Ui::MainWindow *ui;
    QTimer *pTimer;

private slots:
    void hideWindow();
};
#endif // MAINWINDOW_H

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QProcess>
#include <QDebug>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    pTimer = new QTimer();
    pTimer->setInterval(1000);
    connect(pTimer, SIGNAL(timeout()), this, SLOT(hideWindow()));
    pTimer->start();
}

void MainWindow::hideWindow()
{
    if (isVisible())
    {
        qDebug() << "hide!";
        hide();
    }
    else
    {
        qDebug() << "show!";
        show();
    }
}

MainWindow::~MainWindow()
{
    delete ui;
}

When you build and run this program, it will periodically hide and show its mainwindow, but the way it does this is not by telling the compositor to set the "visible" property of the widget, and instead destroying and re-creating the surface.

Also note that you need to set some environment variables before starting the app: To start a Qt application using the ivi-application protocol with the right id, you need to set QT_WAYLAND_SHELL_INTEGRATION to ivi-shell and QT_IVI_SURFACE_ID to 1337