With the new multi-windowing design in iPadOS 26, the behavior of openWindow() has changed.
In iPadOS 18, if I called openWindow(), I would go from a full-screen window to two side-by-side windows. That allowed my app to meet the goal of the user; keep some information on the screen while being able to navigate through the app in the other window.
In iPadOS 26 (beta 3), this no longer works. Instead, a new Window opens ON top of the current window. I am looking for some mechanism to help the user see that two windows are now present and then easily move them on the screen (tiled, side-by-side) or whatever else they would prefer.