Resize the height of a dialog make jump the position for a moment. Regression Mac Only

It's a mac only issue and it's not present on 4.8.4, it's a regression since Qt 5.0

I need to manually resize my windows with the resize function or setFixedSize function, where it happens to work perfectly for the width, when I resize the height, the position of the windows move on the y() (jump up) and go back to it's original position (jump down) during the resize. The final position is correct but there is a glitch during the resize (jump up and down).

I attached a small example of the situation that work fine on Qt 4.8 and bug on Qt 5.0. The example include 2 buttons in the layout of a dialog, one increase the width and the second one increase the height with an arbitrary value (25px). When you increase the with, the window doesn't move but when you increase the height, you can see a jump that occurs on the Mac OS X 10.7 platform.