Instantiating a tool window in qml from c++

[Smatcher]

Hi everyone,

I'm trying to instantiate from c++ a qml window such that it behaves like a tool window for the main window (also in qml).
My problem is that the window content appears inside the main window instead of in a proper separated window.

I tried to do this from qml and it works, however this isn't an option for the application i'm developing without reworking the way I handle windows.

Here is the example I wrote.

• main.cpp

int main(int argc, char *argv[])
{
  QGuiApplication app(argc, argv);
  QQmlApplicationEngine engine;
  WindowAllocator* allocator = new WindowAllocator(&engine);
  allocator->showMainWindow();
  return app.exec();
}

• windowallocator.cpp

#include "windowallocator.h"

#include <QQmlComponent>
#include <QQmlContext>

WindowAllocator::WindowAllocator(QQmlApplicationEngine* engine)
  : QObject(engine)
  , _engine(engine)
  , _main_window(nullptr)
{
  _engine->rootContext()->setContextProperty("win_allocator", this);
}

WindowAllocator::~WindowAllocator()
{}

void WindowAllocator::showMainWindow()
{
  QQmlComponent component(_engine, QUrl(QStringLiteral("qrc:/main.qml")));
  _main_window = dynamic_cast<QQuickWindow*>(component.create(_engine->rootContext()));
  _main_window->show();
}

void WindowAllocator::showToolWindow()
{
  QQmlComponent component(_engine, QUrl(QStringLiteral("qrc:/Tool.qml")));
  QQuickWindow* tool_window = dynamic_cast<QQuickWindow*>(component.create(_engine->rootContext()));
  // Reparent the tool window to the main window
  // Note this is not a visual item parenting (QQuickWindow is not a QuickItem)
  tool_window->setParent(_main_window); 
  tool_window->show();
}

• main.qml

import QtQuick 2.5
import QtQuick.Controls 1.3
import QtQuick.Window 2.2

Window {
  id: root
  visible: true
  width: 640
  height: 480
  title: qsTr("Hello World")

    Tool {
        id: tool
    }

    Column {
       anchors.horizontalCenter: parent.horizontalCenter
       anchors.verticalCenter: parent.verticalCenter

       Button {
           text: "Open embedded"
           onClicked: tool.show()
       }

        Button {
            text: "Open qml allocated"
            onClicked: {
                var component = Qt.createComponent("Tool.qml");
                var win = component.createObject(root);
                win.show();
            }
        }

        Button {
            text: "Open cpp allocated"
            onClicked: {
                win_allocator.showToolWindow()
            }
        }
    }
}

• Tool.qml

import QtQuick 2.5
import QtQuick.Window 2.0

Window {
    flags: Qt.Tool
    width: 300
    height: 200

    Rectangle {
        color: "steelblue"
        anchors.fill: parent

        Text {
            text: "This is a tool window"
            anchors.centerIn: parent
        }
    }
}

I suppose this is either me not reparenting things properly or a bug/limitation in Qt.
This behavior was only tested on Windows 7

Do you have any idea how to make this work ?

Thanks for your time.

[Smatcher]

Nevermind. I found the solution.

The parenting between the main window and the tool window should not be done with setParent but with setTransientParent.

I hope this helps someone someday