How to put 2 Widgets in a MainWindow ?

[Zlatomir]

You can use something like this:

QSizePolicy PlotPolicy = plot->sizePolicy();
PlotPolicy.setVerticalStretch(1);                                   //don't remember the exact "formula", try with 1
plot->setSizePolicy(PlotPolicy);

QSizePolicy PlotPolicy = plot->sizePolicy();
PlotPolicy.setVerticalStretch(1);                                   //don't remember the exact "formula", try with 1
plot->setSizePolicy(PlotPolicy);

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if that doesn't do the right proportions, try this:

QSizePolicy PlotPolicy = plot->sizePolicy();
PlotPolicy.setVerticalStretch(2);                                   //don't remember the exact "formula", so play with this values
plot->setSizePolicy(PlotPolicy);
 
QSizePolicy DataPolicy = data->sizePolicy();
DataPolicy.setVerticalStretch(1);
plot->setSizePolicy(DataPolicy);

QSizePolicy PlotPolicy = plot->sizePolicy();
PlotPolicy.setVerticalStretch(2);                                   //don't remember the exact "formula", so play with this values
plot->setSizePolicy(PlotPolicy);

QSizePolicy DataPolicy = data->sizePolicy();
DataPolicy.setVerticalStretch(1);
plot->setSizePolicy(DataPolicy);

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[gen_mass]

Thanks Zlatomir !
I used your second method and it works well !!!

A last last question...is it possible to center my QTableWidget with that QVBoxLayout?
I want to do that because when I resize my window manually with a mouse, the QTableWidget stays align at the left.
Is there a similar function to

QTableWidget::setAlignement(Qt::AlignCenter)

QTableWidget::setAlignement(Qt::AlignCenter)

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that exists ?
I search the documentation, but couldn't find any easy way to do this