Locking/Docking two app windows together

Has anyone tried locking or docking two app windows together so they stay together and resize together, but have a splitter bar to adjust their relative sizes? I’m specifically interested in using Preview and TextEdit in this fashion.

If you have any examples, advice or reading references to offer they would be appreciated.

Take a look at this video. https://macmost.com/mission-control-and-split-view.html I think it will take you where you want to go. It was made using an older OS but the basics still apply. Stick with it until about the 3 min 20 second point where Gary discusses split screen mode. I’m assuming you’re not trying to script the function but are just trying to set up 2 apps on one window and then work with them.

Thank you. I’ll have a look at the video right away.

[Later Note]: The video does show two apps on on one desktop, but I’m trying to make two apps behave as separate panes in one window on a given desktop.

Sorry. I thought that the split window would be pretty close to what you were looking for. I hope somebody knows of a 3rd party application that has the functions you are looking for and will share it with you.