http://stackoverflow.com/questions/3492739/auto-expanding-layout-with-qt-designer
After creating your QVBoxLayout in Qt Designer, right-click on the background of your widget/dialog/window (not the QVBoxLayout, but the parent widget) and
select Lay Out -> Lay Out in a Grid from the bottom of the context-menu. The QVBoxLayout should now stretch to fit the window and will resize automatically when the entire window is resized.
右擊窗體->布局->柵格布局