HBOX component of Flex keeps all the innner components placed one after another horizontally and if the total width of the inner components exceeds HBOX then a scroll appears but in any case it will not put child elements vertically one after another.
If you want to see how HBOX looks then please follow the link below
and in navigate through Navigation panel as mentioned below
Visual Components --> Containers --> HBOX
I hope there would be solution for this question
thanks In advanse