Mac, QPushButton is one pixel lower than a QComboBox placed at the same y position

A QPushButton is placed at one pixel lower than a QComboBox placed at the same y coordinate.

Reproducible with the following steps:
*In Designer, create a widget.
*Place a QPushButton on the widget, set the y under geometry to 130.
*Place a QCombobox on the widget, set the y under geometry to 130.
*A third widget can be useful so that one can see both widgets without the blue focus rectangle.
*Preview the Widget, move the widget down so the edge of the screen is aligned with the top of the QPushbutton,
it is possible to see that the QCombobox is placed higher.

This cannot be fixed until we introduce the "baseline" concept. This is not possible with Qt 4.x without obsoleting the older QLayout API.