problem while resizing mainwindow.

[phillip_Qt]

in my main window i've 5 lables in a horaizenatllayout. all lable sizepolicy are setting to Prefered.
in my ctor i did like

ui->horizontalLayout->setSizeConstraint(QLayout::SetDefaultConstraint);

ui->horizontalLayout->setSizeConstraint(QLayout::SetDefaultConstraint);

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But the lables size are not resizing with the main window.
I've attched the ui. plz help me how to solve it. Thank u all.