Это ?
void QSplitter::moveSplitter ( int pos, int index ) [protected]
Moves the left or top edge of the splitter handle at index as close as possible to position pos, which is the distance from the left or top edge of the widget.
For right-to-left languages such as Arabic and Hebrew, the layout of horizontal splitters is reversed. pos is then the distance from the right edge of the widget.
See also splitterMoved(), closestLegalPosition(), and getRange().