QTextEdit - margins, indents within QTextEdit

[Acamapichtli]

Yes, I place QTextEdit in QVBoxLayout:

TestApp::TestApp()
{
    textEdit = new QTextEdit;
 
    layoutMain = new QVBoxLayout;
    layoutMain->addWidget(textEdit);
    layoutMain->setMargin(0);
 
    window = new QWidget;
    window->setLayout(layoutMain);
    setCentralWidget(window);
}

TestApp::TestApp()
{
    textEdit = new QTextEdit;

    layoutMain = new QVBoxLayout;
    layoutMain->addWidget(textEdit);
    layoutMain->setMargin(0);

    window = new QWidget;
    window->setLayout(layoutMain);
    setCentralWidget(window);
}

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I tried using setContentsMargins in both textEdit and layoutMain, but it doesn't set margins at all or it works like in on picture 1.
I don't know if you understood me correctly, I would like custom margins inside the textEdit, not the layoutMain margins.