I'm not sure what you are doing. If the mainframe has a layout and all widget are inside nested layout, you cannot go below the minimum size of each individual widget and nothing will overlap. So, somehow you have used the layouts wrong. Without any code/.ui files it is really hard to diagnose the problem.

@Joe-von-Habsburg My example recast with a changing background:

// widget.h #ifndef WIDGET_H #define WIDGET_H #include <QWidget> class Widget : public QWidget { Q_OBJECT public: Widget(QWidget *parent = nullptr); ~Widget(); // QWidget interface protected: void mousePressEvent(QMouseEvent *event); void mouseReleaseEvent(QMouseEvent *event); void paintEvent(QPaintEvent *event); private slots: void setBackground(); private: QImage mBackground; QPointF mFrom; QPointF mTo; }; #endif // WIDGET_H // widget.cpp #include "widget.h" #include <QPaintEvent> #include <QPainter> #include <QLinearGradient> #include <QRandomGenerator> #include <QTimer> #include <QDebug> Widget::Widget(QWidget *parent) : QWidget(parent) , mBackground(500, 500, QImage::Format_RGB32) { setBackground(); QTimer *t = new QTimer(this); connect(t, &QTimer::timeout, this, &Widget::setBackground); t->start(1000); } Widget::~Widget() { } void Widget::mousePressEvent(QMouseEvent *event) { mFrom = event->position(); mTo = mFrom; } void Widget::mouseReleaseEvent(QMouseEvent *event) { mTo = event->position(); update(); } void Widget::paintEvent(QPaintEvent *event) { QPainter p(this); p.drawImage(event->rect(), mBackground); if (mFrom != mTo) { QPen pen(Qt::red); pen.setWidth(3); p.setPen(pen); p.drawLine(mFrom, mTo); } p.end(); } void Widget::setBackground() { QPainter p(&mBackground); const QRectF rectf(mBackground.rect()); QLinearGradient grad(rectf.topLeft(), rectf.bottomRight()); grad.setColorAt(0, QColor::fromRgb(QRandomGenerator::global()->generate())); grad.setColorAt(1, QColor::fromRgb(QRandomGenerator::global()->generate())); p.fillRect(mBackground.rect(), QBrush(grad)); p.end(); update(); }

@dan1973 said in QWidget control:

b1->resize(this->size());

I wouldn't even bother doing this in the constructor --- did you qDebug() << this->size() there like I suggested? But up to you, I guess it does no harm, it will get overwritten by call to Widget::resizeEvent() as soon as shown, I think.

@Hai-Anh-Luu Welcome to the forum.

Until the widget is displayed its size, and the size of any child widget in a layout, is unknown. In the widget class constructor^^ the widget is not yet shown so you get either the size hint from the widget concerned or some other value.

^^ That is when executing this line window = NewGrid()

One way to see the size that is initially allocated is to do so in a slot connected to a zero-length (or very short) single-shot QTimer. This will fire when the event loop is reached, after the UI is shown. That is when app.exec() is running.

@Pl45m4 said in Custom Widget not showing in layout:

always returning QSize(width(), height()); doesn't feel like the best solution ;-)

I guess that QPushButton uses the actual text displayed (plus some padding) to calculate the size hint. QFontMetrics might help here.

@SGaist Thanks for your suggestion. I will try to implement things with QtQuick.

@Pl45m4 said in Custom widget using and extending Qt's pImpl:

It was just about the naming?!
Is this the way? :)

I would say yes.

@julienchz
Hi
I have created some opengl tutorials check here: https://bitbucket.org/joaodeusmorgado/opengltutorials/src/master/
I am using QOpenGLWidget, but I use mostly raw opengl, you could easily create a abstract render class, and then reuse it to QOpenGLWidget, or any other frame work of your choice render class.
Hope it helps

@JonB
@JoeCFD

OK found that Wayland just doesn't allow to windows to move themselves.

Not a necessary feature for me and can't solve the black screen problem when logging with Xorg.
Will just ask gnome to center new windows with tweaks.

Closing the topic.

Thanks to both you.

Not read the whole thread but maybe this is of interest: https://wiki.qt.io/TaskTree

@RudrakshS

So you dont want to provide any more information?
e.g.

what layout, if any? move which widgets from where to where? how does the destination look like? empty widget or any other stuff in it?

You dont have to apologize, but YOU have an issue with your code, not us :)
If you dont show what you've done, one can only guess.

If it is, what I think it is, then you are missing a layout somewhere or make any unallowed "moves".

Well, Qt has both a QMenu and a QMenuItem. Only the QMenuItem is supposed to trigger actions. The QMenu itself only has QMenuItems and submenus. So, its action is already defined.

Usually, the QMenuItems have QActions associated with it. For the QMenu::triggered signal the documentation states:

This signal is emitted when an action in this menu is triggered.

To me this reads that you have several entries inside the QMenu and one of these entries triggers an action. This is also why this signal contains the QAction as a parameter. My understanding would mean that clicking on the QMenu itself does not emit a triggered signal, but only clicking on a QMenuItem does.

From the Qt documentation (qt6), QTabWidget::setCornerWidget: says:

Note: Corner widgets are designed for North and South tab positions; other orientations are known to not work properly.

That means they do work, but are messy to and inconvenient to use.

Here's a way to use QTabWidget corner widget on the side:

As already noted in the question, setting a corner widget while tabs position is West or East, causes a small gap before the tabs without anything appearing there.

But if you set QTabWidget's corner widget minimum size, it will appear, which solves a problem but causes another, because now I need to calculate that size myself, or make room for my corner widget.

Here's an MRE that I used to try and figure how to get that empty corner size:

QTabWidget *t = new QTabWidget(); //I needed the stacked widget so I can use its geometry to calculate the empty corner size QStackedWidget *stack_widget = t->findChild<QStackedWidget*>("qt_tabwidget_stackedwidget"); t->setMinimumSize(800,600); t->addTab(new QWidget(),"Tab1"); t->addTab(new QWidget(),"Tab2"); t->addTab(new QWidget(),"Tab3"); t->addTab(new QWidget(),"Tab4"); t->setTabPosition(QTabWidget::TabPosition::West); QToolButton *button1 = new QToolButton(); button1->setIcon(QIcon(":/icons/collapse.png")); t->setCornerWidget(button1,Qt::TopLeftCorner); t->show(); //width is equal to where the stack widget starts (x coordinate) //height is equal to where the tab bar starts (y coordinate) //I subtracted 1 from stackwidget's x because it simply looked better t->cornerWidget(Qt::TopLeftCorner)->setMinimumSize(stack_widget->geometry().x()-1, t->tabBar()->geometry().y()); //checking related widgets geometries /*qDebug()<<"cornerWidget geo"<<t->cornerWidget(Qt::TopLeftCorner)->geometry(); qDebug()<<"tabBar rect"<<t->tabBar()->tabRect(0); qDebug()<<"tabBar geo"<<t->tabBar()->geometry(); qDebug()<<"stackwidget geo"<<sw->geometry();*/

Here's how it looks, I used a custom icon:

Corner widget appeared

If you need more space for the corner widget, you'll need to move the tab bar, because corner widget will cover it, you can do that using stylesheet. See this: Qt Style Sheets Examples: Customizing QTabWidget and QTabBar.

Here's an example of stylesheet:

t->setStyleSheet("QTabWidget::tab-bar " "{" "top: 50px;" /* push down by 50px */ "}");

Here's how it looks with that being the only addition and change to my MRE:

Extended tab widget corner widget

Suggestion: QTabWidget::paintEvent might be a better solution.

@misscoffee
So just set the size of the view and/or scene to the full size of the screen/desktop. You can also use void QWidget::showFullScreen() (see the warnings there).

Be aware that widgets/windows have borders, and a title bar unless you specify otherwise, so the view/scene may not occupy every pixel of the screen, unless you take action, if that matters to you. IIRC, graphics scene/view places coordinate (0,0) in the center with x,y increasing right/up. You can use setSceneRect() to alter this.

Hey @mrjj
Digging out this topic... as I figure better to stick it in the same tree...

Anyway, any idea how to make QScrollArea behave correctly too? Making it container does not let me drag widgets on it :/

@Saviz

#include <QApplication> #include <QMouseEvent> #include <QVideoWidget> class HoverVideoWidget : public QVideoWidget { public: HoverVideoWidget(QWidget *parent = nullptr) : QVideoWidget(parent) { setMouseTracking(true); // Enable mouse tracking to get hover events } protected: void enterEvent(QEvent *event) override { // Called when the mouse enters the widget setStyleSheet("background-color: lightblue;"); // Set the background color to light blue } void leaveEvent(QEvent *event) override { // Called when the mouse leaves the widget setStyleSheet(""); // Reset the background color to default } }; int main(int argc, char *argv[]) { QApplication app(argc, argv); HoverVideoWidget player; player.show(); return app.exec(); }

According your first picture you're missing a layout on the widget.