Layout cell collapse button dissapeared

I am trying a Layout (“4T”), and attached a tabbar its cell (“b”).

After attaching tabbar, the cell’s collapse-button is hidden. I think it is overwritten by tabbar’s “moving-buttons”.

How do I make the Layout cell still collapsible after attaching tabbar?

p.s. I tried with IE 11 and Chrome, but all same.

Attaching tabbar hides layout cell’s header. You just need to show it via layout.cells(“b”).showHeader() after tabbar is attached