QDockWidget does not stay on the right when QMainWindow resizes

[vitorg]

Hi all,

I have a QMainWindow with several QDockWidget objects in it. One of them is supposed to have fixed sized and stay on the right, and when I launch the application this does happen. But when I resize the QMainWindow (or maximize it) there appears a space between this QDockWidget and the rightmost part of the QMainWindow. The same thing happens if I put the QDockWidget on the left.

See this video to better understand what I mean:
https://drive.google.com/open?id=1Ho42-zurEABTwSPETnxCtqdtynexaALg

As you can see, after I make the QDockWidget float and then dock it back in the QMainWindow, it all works as I would like it to from the beginning.

Any idea if this is a configuration I am missing somewhere? I guess the QDockWidget itself wouldn't be the problem but...

Thank you and cheers,
Vítor

[SGaist]

Hi,

What version of Qt are you using ?
What exact OS ?
Can you provide a minimal compilable example that reproduce that behaviour ?

[vitorg]

Hi SGaist,

Thanks for your time.

The OS is linux and if I do uname --all I get:

Linux ws-vitor 4.18.0-20-generic #21~18.04.1-Ubuntu SMP Wed May 8 08:43:37 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

I am running this under xubuntu.

The Qt version is that of the system: 5.9.5

I've indeed managed to put up an example where this happens. It follows our gui, but simpler with only two tabs and a "Status" that we want to have on the right.
Here you go:

#ifndef TESTGUI_H
#define TESTGUI_H

#include <QMainWindow>
#include <QDockWidget>

class TestGui : public QMainWindow {
public:
    TestGui() {
        setDockOptions(QMainWindow::AnimatedDocks | QMainWindow::AllowTabbedDocks);

        QDockWidget* dockwidget = new QDockWidget("Tab #1");
        dockwidget->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
        dockwidget->setFeatures(QDockWidget::DockWidgetFloatable | QDockWidget::DockWidgetMovable);
        dockwidget->setMinimumWidth(1000);
        addDockWidget(Qt::TopDockWidgetArea, dockwidget);

        QDockWidget* prevdockwidget = dockwidget;
        dockwidget = new QDockWidget("Tab #2", this);
        dockwidget->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
        dockwidget->setFeatures(QDockWidget::DockWidgetFloatable | QDockWidget::DockWidgetMovable);
        dockwidget->setMinimumWidth(1000);
        addDockWidget(Qt::TopDockWidgetArea, dockwidget);
        tabifyDockWidget(prevdockwidget, dockwidget);

        // Problematic component
        dockwidget = new QDockWidget(tr("Status"), this);
        dockwidget->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Expanding);
        dockwidget->setFeatures(QDockWidget::DockWidgetFloatable | QDockWidget::DockWidgetMovable);
        dockwidget->setMinimumWidth(160);
        dockwidget->setMaximumWidth(160);
        dockwidget->setAllowedAreas(Qt::AllDockWidgetAreas);
        addDockWidget(Qt::RightDockWidgetArea, dockwidget);

        setCorner(Qt::TopRightCorner, Qt::RightDockWidgetArea);
        resize(1100, 700);
    }
    ~TestGui() = default;
};

#endif // TESTGUI_H

If you maximize the window, the status stays basically in the middle instead of going all the way to the right.
Thanks a lot again.

[SGaist]

Do you mean it stays locked on the left side of the right dock panel ?

[vitorg]

@SGaist said in QDockWidget does not stay on the right when QMainWindow resizes:

u mean it stays locked o

Not that it stays on the left: that's where I want to have it.

The problem is that it doesn't maintain its size: it becomes very wide, instead of keeping the 160 I wanted. And if you un-dock it and dock it back in again it will now have the proper size. I want to happen default when I resize (maximize) the main window.

[vitorg]

Anyone, any idea? It seems like a bug in qt. Is it maybe solved in 5.13? Or previous versions even?

Thank you very much.

[Gojir4]

@vitorg Hi, It may be related to this bug : https://bugreports.qt.io/browse/QTBUG-65592
See this post
Workaround is only one line of code so you will quickly know if that's the issue or not.