The changes in one editor are mirrored in the other in real time. You can float the editors as windows, and view the notation as such while the drum or piano roll are docked in the bottom pane. Notion was already pipelined to Studio One for easy exchange of data.
At the bottom is the mixing console which swaps out with the various editors: piano roll, drum, Melodyne 5 visual audio editing (a license is included) via ARA2, and new for version 5-musical notation courtesy of the company’s Notion 6 score editing software. The layout of the main window consists of an inspector panel and controls for the current track to the far left, track headers to the right of those, the timeline area for clips (which may be layered), then the browser to the far right. Version 4 already had a pipeline for exchanging info with the standalone version of Notion. Studio One 5 integrates some of the scoring abilities of its Notion musical notation program. I mention this as Studio One bears more than a passing resemblance to those in both appearance and approach. The original developers were also responsible for Nuendo, a surround version of the venerable and popular Cubase from Steinberg.