Warning when closing an undocked qwidget

Christian Ehrlicher

So you somehow get into QDockWidgetPrivate::initDrag(). Is it possible to set a breakpoint there to see why it is entered?

Mwoua_Leddar

When closing the widget with the mouse (top right button)

Call stack is

Qt5Widgetsd.dll!QDockWidgetPrivate::initDrag(const QPoint & pos, bool nca) Line 778 C++
Qt5Widgetsd.dll!QDockWidgetPrivate::nonClientAreaMouseEvent(QMouseEvent * event) Line 1043 C++
Qt5Widgetsd.dll!QDockWidget::event(QEvent * event) Line 1586 C++
Qt5Widgetsd.dll!QApplicationPrivate::notify_helper(QObject * receiver, QEvent * e) Line 3630 C++
Qt5Widgetsd.dll!QApplication::notify(QObject * receiver, QEvent * e) Line 3580 C++
Qt5Cored.dll!QCoreApplication::notifyInternal2(QObject * receiver, QEvent * event) Line 1063 C++
Qt5Cored.dll!QCoreApplication::forwardEvent(QObject * receiver, QEvent * event, QEvent * originatingEvent) Line 1079 C++
Qt5Widgetsd.dll!QWidgetWindow::handleNonClientAreaMouseEvent(QMouseEvent * e) Line 505 C++
Qt5Widgetsd.dll!QWidgetWindow::event(QEvent * event) Line 308 C++
Qt5Widgetsd.dll!QApplicationPrivate::notify_helper(QObject * receiver, QEvent * e) Line 3630 C++
Qt5Widgetsd.dll!QApplication::notify(QObject * receiver, QEvent * e) Line 2970 C++
Qt5Cored.dll!QCoreApplication::notifyInternal2(QObject * receiver, QEvent * event) Line 1063 C++
Qt5Cored.dll!QCoreApplication::sendSpontaneousEvent(QObject * receiver, QEvent * event) Line 1471 C++
Qt5Guid.dll!QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent * e) Line 2278 C++
Qt5Guid.dll!QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent * e) Line 2003 C++
Qt5Guid.dll!QWindowSystemInterface::sendWindowSystemEvents(QFlags<enum QEventLoop::ProcessEventsFlag> flags) Line 1181 C++

And for the last function:

void QDockWidgetPrivate::nonClientAreaMouseEvent(QMouseEvent *event)
{
    Q_Q(QDockWidget);

    int fw = q->style()->pixelMetric(QStyle::PM_DockWidgetFrameWidth, nullptr, q);

    QWidget *tl = q->topLevelWidget();
    QRect geo = tl->geometry();
    QRect titleRect = tl->frameGeometry();
    {
        titleRect.setLeft(geo.left());
        titleRect.setRight(geo.right());
        titleRect.setBottom(geo.top() - 1);
        titleRect.adjust(0, fw, 0, 0);
    }

    switch (event->type()) {
        case QEvent::NonClientAreaMouseButtonPress:
            if (!titleRect.contains(event->globalPos()))
                break;
            if (state != nullptr)
                break;
            if (qobject_cast<QMainWindow*>(parent) == 0 && qobject_cast<QDockWidgetGroupWindow*>(parent) == 0)
                break;
            if (isAnimating())
                break;
            initDrag(event->pos(), true); //This line
            if (state == nullptr)
                break;
            state->ctrlDrag = (event->modifiers() & Qt::ControlModifier) ||
                              (!hasFeature(this, QDockWidget::DockWidgetMovable) && q->isFloating());
            startDrag();
            break;
        case QEvent::NonClientAreaMouseMove:
            if (state == nullptr || !state->dragging)
                break;

#ifndef Q_OS_MAC
            if (state->nca) {
                endDrag();
            }
#endif
            break;
        case QEvent::NonClientAreaMouseButtonRelease:
#ifdef Q_OS_MAC
                        if (state)
                                endDrag();
#endif
                        break;
        case QEvent::NonClientAreaMouseButtonDblClick:
            _q_toggleTopLevel();
            break;
        default:
            break;
    }
}

Christian Ehrlicher

This is strange, I don't see anything within QDockWidget sources. But there were mouse handling changes in 5.12 - can you maybe check with 5.11.x and 5.12.x to see if this may be the culprit?

Mwoua_Leddar

Just run basic tests with version 5.11.3 and 5.12.0.
Looks like I dont have the issue with any of them

Christian Ehrlicher

Can you check latest 5.12.x?

Mwoua_Leddar

I have managed to reproduce it with a really basic example:

#include <QApplication>
#include <QMainWindow>
#include <QLabel>
#include <QDockWidget>


int main(int argc, char* argv[])
{
    QApplication lApp(argc, argv);

    QMainWindow a;
    a.setCentralWidget(new QLabel("Main"));
    a.show();

    auto lWindow = new QDockWidget(&a);
    lWindow->setFloating(true);
    lWindow->show();

    return lApp.exec();
}

and the cmake file im using:

cmake_minimum_required(VERSION 3.16.0)
set(CMAKE_VERBOSE_MAKEFILE ON CACHE BOOL "ON" FORCE)

project(test)

#Qt libs and macro
SET(CMAKE_PREFIX_PATH "C:/Qt/5.15.1/msvc2019_64")

set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTORCC ON)
set(CMAKE_AUTOUIC ON)

find_package(Qt5 COMPONENTS Widgets Gui REQUIRED)

set(Src
    ${CMAKE_CURRENT_LIST_DIR}/main.cpp
)

add_executable(Test ${Src})
target_link_libraries(Test PRIVATE Qt5::Widgets Qt5::Gui)

Mwoua_Leddar

Ran more test with this simple example, the issue is actually there with qt 5.11.3 ,5.12.0 and 5.12.9.

Edit:
I confirm the issue is not here with 5.7.1

Should I test with more versions?
Raise a bug?

Do you know if there is a workaround?

Christian Ehrlicher

So you can also reproduce it with 5.11? Then it's not the change I thought.
It would be nice when you find some time to investigate with which version the issue came in.

jsulm

This post is deleted!

Mwoua_Leddar

The issue is there in 5.9.

Cant test between 5.7.1 and 5.9, versions are not available for download

Christian Ehrlicher

Thx for the information. I would suggest you to create a bug reports with all your findings. Sadly I can't compile such an old version on my system anymore so I can't hep figuring out which exact commit creates this issue.

Mwoua_Leddar

Bug report created: https://bugreports.qt.io/browse/QTBUG-88157
(Cant figure out how to properly format the code in the report)

Christian Ehrlicher

Thx, I reformatted the code, the CMakeLists.txt is not needed.