Qt widgets-基本控件使用示例，不使用控件拖动，采用代码layout完成控件排布。 BasicLayout Basic Layouts shows how to use the standard layout managers that are available in Qt: QBoxLayout, QGridLayout, and QFormLayout. The QBoxLayout class lines up widgets horizontally or vertically. QHBoxLayout and QVBoxLayout are convenience subclasses of QBoxLayout. QGridLayout lays out widgets in cells by dividing the available space into rows and columns. QFormLayout, on the other hand, sets its children in a two-column form with labels in the left column and input fields in the right column. lays out widgets in cells by dividing the available space into rows and columns. QFormLayout, on the other hand, sets its children in a two-column form with labels in the left column and input fields in the right column.