splitter->setStretchFactor(0, 3); // widget gets 3 out of 4 width/height units
splitter->setStretchFactor(1, 1); // widget gets 1 out of 4 width/height units
splitter->setStretchFactor(0, 3); // widget gets 3 out of 4 width/height units
splitter->setStretchFactor(1, 1); // widget gets 1 out of 4 width/height units