Second QQuickWindow doesn't render unless resized

See attached test-case.

A 2 second QTimer triggers a property change, that is hooked to a Text {}.

Only one of the windows displays "Hello World", the second window will display it after you resize it.

I can only reproduce this if the property is changed in the background, not if I use a MouseArea and do it onClicked.

Reproduced with Qt 5.2.1 also.