Resizable Panels

You need a little more space for structure panel, you can simply drag it to adjust its size, or you maybe want little smaller panel for styling you can do that by dragging.

You are maybe writing some CSS or other code, Oxygen Builder will take 50% of the screen by default. With Resizable panels you won't face this problem because they will stay at the same size until you make size adjust.

You need more/less space?
Just simply drag it to the size you want.

You want different default panel size?
By default panels are 300px wide, and drag to resize changes are temporary changes. If you need permanent default width change you can set default size for the each panel under User preference menu. So you have fully flexibility to adjust interface for you current screen size on permanent and temporary basis.