flow in scrollview, buggy parent: id must be specify to set size

Scenario: I want to set the size of my flow according to its parent size, a Scollview. I tried to set it using "width: parent.width and height: parent.height".

Results: It doesn't work,  Flow elements stay in a column whether they could fit in a line.

Fix: I need to use the id to get an expected behavior:  "width: myscrollwiew.width and height: myscrollwiew.height"

Anchor to either parent or myscrollwiew doesn't work either

I attached two qml files:

-One working (size set with id) 

-Another not working (size set according to parent)