Item is not updated if it would be invisible under software render

When using software rendering, if an item would be invisible (for example if it would be covered by another item), it seems it is optimized away. However, the old item is still left on the screen. 

In the attached testapp, the user tried to move both the blue and red rectangle to the same position by changing the x position, the blue one will be covered by the red one. The blue one stays at the old position on GUI, but it’s position in QML is changed. If the opacity of the red rectangle is changed to 0.99, then the blue one is moved.