void QSizePolicy::setHorizontalStretch ( uchar stretchFactor )
Sets the horizontal stretch factor of the size policy to the given stretchFactor.
Как-то не информативно описано. Что это за фактор растягивания такой, множитель? Для чего он нужен
Stretch Factors
Widgets are normally created without any stretch factor set. When they are laid out in a layout the widgets are given a share of space in accordance with their QWidget::sizePolicy() or their minimum size hint whichever is the greater. Stretch factors are used to change how much space widgets are given in proportion to one another.
Похоже разобрался. Это некий фактор вытеснения других виджетов в лэйауте.
Об этом понятнее тут написано:
Stretch Factor in QGraphicsLinearLayout
You can assign a stretch factor to each item to control how much space it will get compared to the other items. By default, two identical widgets arranged in a linear layout will have the same size, but if the first widget has a stretch factor of 1 and the second widget has a stretch factor of 2, the first widget will get 1/3 of the available space, and the second will get 2/3.
QGraphicsLinearLayout calculates the distribution of sizes by adding up the stretch factors of all items, and then dividing the available space accordingly. The default stretch factor is 0 for all items; a factor of 0 means the item does not have any defined stretch factor; effectively this is the same as setting the stretch factor to 1. The stretch factor only applies to the available space in the lengthwise direction of the layout (following its orientation). If you want to control both the item's horizontal and vertical stretch, you can use QGraphicsGridLayout instead.
