Examples or help with fixed sized screen partitions?

I’d like to create an app whos page is laid out like an IDE…where there are areas that are of a fixed size, and can be resized by dragging the divider between two areas. I’ve been struggling to even a single sidebar thing to work. Can anyone point me to example or sample code that would show me how to go about such things. Have I missed something in the docs or in the components library? I was hoping to find a “Divider” component, but no such luck. TIA!