How to remove the margin between QWidgets in layout

[DDWW]

mainLayout->setContentsMargins(0,0,0,0);
This can't remove the margin in the center.

here is my code:

    QWidget* titleBar = new QWidget(this);
    QHBoxLayout*    hLayout = new QHBoxLayout();
    QLabel* mTitle = new QLabel("hgis");
    hLayout->addWidget(mTitle);
    hLayout->addStretch();
    titleBar->setLayout(hLayout);
    titleBar->setStyleSheet("background-color:blue;");

    //
    QMainWindow* coreWidget = new QMainWindow(this);
    coreWidget->menuBar()->addAction(new QAction(QString("test1"),this));
    coreWidget->setWindowFlags(Qt::FramelessWindowHint);
    coreWidget->setStyleSheet("background-color:black;margin: 0px;");

    //
    QVBoxLayout* mainLayout = new QVBoxLayout();
    mainLayout->addWidget(titleBar);
    mainLayout->addWidget(coreWidget);
    mainLayout->setContentsMargins(0,0,0,0);

    setLayout(mainLayout);
    setStyleSheet("background-color:red;");

I want to remove the red line between QLabel and QMainwindow.

[p3c0]

Hi @DDWW and Welcome,
setSpacing for mainLayout to 0.

[Chris Kawa]

Margin is the space around the content. Item spacing is controlled like this:

mainLayout->setSpacing(0);

[DDWW]

3Q very mush.I have been troubled by this problem for a long time.

[DDWW]

@p3c0
And can I use qss to have a similar effect?

[p3c0]

@DDWW Stylesheets cannot be applied to QLayouts. So no way doing that. But if you dont use layout then setting min-height for both widgets may work.