Qt remove margins

Question

I am currently using a QMainWindow widget and I would like to remove margins around the widget inside. I success to remove margins for window borders but not for the widgets inside my window.

Here is my code, for example :

this->mainWidget = new QWidget(this);
this->mainLayout = new QHBoxLayout;
QLabel *foo = new QLabel("foo", this);
QLabel *bar = new QLabel("bar", this);

mainLayout->setContentsMargins(0, 0, 0, 0); // Remove margins for window borders

this->setWindowFlags(Qt::FramelessWindowHint);

foo->setStyleSheet("background-color: green");
bar->setStyleSheet("background-color: red");
foo->setContentsMargins(0, 0, 0, 0); // Has no effect
bar->setContentsMargins(0, 0, 0, 0); // Has no effect

this->mainLayout->addWidget(foo);
this->mainLayout->addWidget(bar);

this->mainWidget->setLayout(mainLayout);
this->setCentralWidget(mainWidget);

And here is what it rendered :

I would like to remove the white part between the two widgets.

Have you an idea how to make that kind of things ?

Thank you.

Answer 1

You simply need to set the spacing attribute of your box layout to zero:

 this->mainLayout->setSpacing(0);