Over the years I've worked with a lot of IDE's. One of the best is Delphi. It's called a RAD (Rapid Application Development) platform. One of the ways it makes things really easy to work with is something called panels. You can drop these panels on a form (layout) and give them various alignments, like top, left, bottom, center or even custom alignments. When you drop components (objects) onto them, they have anchors and they anchor themselves to the panels. You can set the anchors to any combination of top, bottom, left or right. The beauty of this is, as the form gets resized, the panels automatically resize based on their alignment and the components anchored to them stay in a position relative to their anchor setting. A top alignment will adjust it's width but not it's height, to match the form size. Left aligns, adjust height, but not width. Panels and anchors are an almost fool-proof way of developing aps and having all of the components stay exactly where you want them, regardless of the size of the form.
That... is something I desperately miss in C3. Call them containers or what you wish, C3's methods for layout placement always forces me to manually place things exactly where I want them in the onStart and browser resize events. And to me, that's pretty clunky.