QGridLayout and QWidget::setContentsMargins

[fross]

Using Qt 4.7.1 I'm trying to place a QCheckbox under a QLineEdit using a QGridLayout.

I don't want the QCheckBox to be aligned with the QLineEdit. I want it to be offset by 20 pixels. In order to do so I use setContentsMargins on the checkbox but it doesn't seem to work. How come?

#include <QtGui>
 
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
 
    QLabel* label = new QLabel("Label: ");
    QLineEdit* lineEdit = new QLineEdit;
    QCheckBox* checkBox = new QCheckBox("Checkbox");
 
    // Layout.
    QGridLayout* layout = new QGridLayout;
    layout->setMargin(0);
 
        // First row.
        layout->addWidget(label, 0, 0);
        layout->addWidget(lineEdit, 0, 1);
 
        // Second row.
        checkBox->setContentsMargins(20, 0, 0, 0);
        layout->addWidget(checkBox, 2, 1, Qt::AlignLeft);
 
    QWidget* widget = new QWidget;
    widget->setLayout(layout);
 
    QMainWindow mainWindow;
    mainWindow.setCentralWidget(widget);
    mainWindow.setWindowTitle("Demo");
    mainWindow.adjustSize();
    mainWindow.show();
 
    return app.exec();
}

#include <QtGui>

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

    QLabel* label = new QLabel("Label: ");
    QLineEdit* lineEdit = new QLineEdit;
    QCheckBox* checkBox = new QCheckBox("Checkbox");

    // Layout.
    QGridLayout* layout = new QGridLayout;
    layout->setMargin(0);

        // First row.
        layout->addWidget(label, 0, 0);
        layout->addWidget(lineEdit, 0, 1);

        // Second row.
        checkBox->setContentsMargins(20, 0, 0, 0);
        layout->addWidget(checkBox, 2, 1, Qt::AlignLeft);

    QWidget* widget = new QWidget;
    widget->setLayout(layout);

    QMainWindow mainWindow;
    mainWindow.setCentralWidget(widget);
    mainWindow.setWindowTitle("Demo");
    mainWindow.adjustSize();
    mainWindow.show();

    return app.exec();
}

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[MattPhillips]

This doesn't address your question directly but could you also just stick in a spacer and adjust your proportions to get the offset you want?