Inconsistent Menu behavior difference between Microsoft and Qt

Menus beside a button with a menu pop up never over the mouse cursor under MS Software.

In Qt a menu from a QToolButton appears on "strange" positions.
Sometimes the menu pops up and the mouse is somewhere in the middle of the
menu. If the menu is placed where the current mouse cursor is selecting an
item at the same time it opens up, you already select this item when you
release the mouse. The menu gets closed immediately and triggered the QAction.
You can reproduce if you move you mouse 1 pixel while clicking and releasing
the toolbutton menu-button.

Not able to reproduce this behavior with any widget in MS software. The menu is
always placed outside the mouse so that a selection needs another user
movement of the mouse after opening the menu.

Steps to reproduce:

• Move app to bottom right screen corner
• Open toolbutton menu, ESC out, repeat
• Observe menu is over mouse (which does not happen when there is enough space)