Setting landscape orientation in QPageSetupDialog causes inconsistent display in QPrintPreviewDialog.
Preview stays in portrait orientation whereas button with landscape icon is checked.
In qpagesetupdialog_win.cpp PageSetupDlg is used to obtain paper size which might be given with width greater than height
whereas QPageSize is defined always in a portrait layout regardless of what current printer orientation is set to.
Setting page size from values obtained directly from PageSetupDlg: ptPaperSize.x and ptPaperSize.y might cause the problem.