Layout resizing problem

[Yaoming]

Hi, I've got this application: Capture.jpg
As you can see, I've got two PushButtons with black arrows. Those buttons are supposed to make the corresponding widget (either the tabWidget on the left or the normal widget on the right) take the entire size of the application window. I've tried to resize using the corresponding function but it's not working... I've also seen that showFullScreen() only works for independant windows...
Can you please tell me why my resize is not working? Here's what I have done so far:

ui.LayoutCahiers->setSizeConstraint(QLayout::SizeConstraint::SetNoConstraint); // I'm trying to destroy all constraints that may interfere with the resize function
	ui.Onglets->resize(200, 500);  //trying to resize with random values (just to see if it works)

ui.LayoutCahiers->setSizeConstraint(QLayout::SizeConstraint::SetNoConstraint); // I'm trying to destroy all constraints that may interfere with the resize function
	ui.Onglets->resize(200, 500);  //trying to resize with random values (just to see if it works)

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Thanks for your replies.

[anda_skoa]

My first idea would be to use a QSplitter for the separation. It allows sections to be collapsed

Another approach would be to hide the part that should no longer be visible.

Cheers,
_