Hi,

Thank you very much for your reply.

I have a main window which I have used showMaximized on.
Qt Code: 
  1. ui->setupUi(this);
  2.     this->showMaximized();
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I've have then added two main items :
a scrollArea and a tabWidget
Qt Code: 
  1. QScrollArea* scrollArea = new QScrollArea;
  2. ui->layout->addWidget(scrollArea,1,0,1,4);
  3. //The tabWidget is created in Designer but filled with line codes and I have placed it for it to fill the rows I wanted
  4. ui->layout->addWidget(ui->tabWidget,1,5,1,9);
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I have one of the tabs that contains my plot (and 4 buttons).
Qt Code: 
  1. layoutTab1->addWidget(button1,0,0);
  2. layoutTab1->addWidget(button2,0,1);
  3. layoutTab1->addWidget(button3,0,2);
  4. layoutTab1->addWidget(button4,0,3);
  5. layoutTab1->addWidget(myPlot,2,0,1,5);
  6. ui->tab1->setLayout(layoutTab1);
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I have tried to put sizeConstraint on my layoutTab1 but it had no effect, and a sizeFixed on my mainLayout didn't do the trick either.

I don't know if it's relevant for my problem, but I need to display different plots depending on the button choosed, so I've put all my plots on the same place and hide/show them when a button is clicked.

I have now added curves to my plot but I still have this issue with my date format and my scale engine. I m aware that I'm probably doing it wrong, but as I said earlyer this one of my first Qt Project. Sorry if I'm still missing informations.

Thanks for your help,

Stank