Is there something like 'pack' for 'auto-adjust' a window to fit the components?

I have a dialog with a Group-Box with variable height. I'd want to use some function to 'pack' the form, that is to say, to 'auto-calculate' the height and width of all the components and then set the height and the width of the window.
Have to do this manually ?
Thanks

You mean layouts?

Look at QWidget::adjustSize