Dialog layout differs from that in Qt Designer

[Klusting]

I use a 3x3 grid layout and set LayoutRowStretch=1,1,1 , so the row heights are equal.
That works fine in Qt Designer, but in the built program, only the last row would stretch when the window size changes.
http://i.imgur.com/7nDLy4l.png
http://i.imgur.com/XulpY91.png