MainWindow are not placed on respective screens

In multiple screen setup, if you try to place multiple window on each available screen with a given geometry.  It fails to put the window on screen if there are more than 2 monitors attached.

In the attached example  mainwindow objects should be placed, one on each screen, at precisely 100,100, of size 100,100, but Qt cannot once you have more than 2 screens. If you do the same with QDialog it works fine, or mainwindow works fine if one or two monitors, but not with 4 monitor.

It seems monitor arrangement (left/top/bottom) does not matter any arrangement of 4 monitors can be used to reproduce.