There is parent layout and it is called mainLayout. I think problem is here:
spinsLayout = new QVBoxLayout(spinsBox);
buttonsLayout = new QHBoxLayout(buttonsBox);

here I create layouts with qgroupbox as a parent. I receive warnigns that tells me that qgroupbox already has a layout. But what if I want to put some layout (with some objects in order inside it) inside a groupbox. Please help.