mapToGlobal() returns wrong values in some Layouts/Views

mapToGlobal() returns wrong values when the item is in Layouts/Views.

As far as I tried, the same issue occurs in :

• PathView
• GridView
• GridLayout
• RowLayout
• ColumnLayout

Steps to reproduce the issue :

0. Prepare an external screen, and configure both of 1st & 2nd screens as 100% scale. 2nd screen is to be placed to the right of the 1st. 
1. Run the attached reproducer, and move the application window to the 2nd screen.
2. Make the application window full-screen.
3. Check the Gx/Gy values displayed in the Rectangles.