That's obviously the only correct approach.

The concept of "window position on screen" makes no sense, since a compositor is allowed to display windows arbitrarily, and doesn't necessarily display them as 2D rectangles (for instance, they could be displayed in a VR environment at arbitrary 3D positions, or they could be warped arbitrarily, etc.).

Also, the window layout belongs to the user and compositor and it would be a security hole to let applications affect it.

If you want to position subwindows, you need to draw the subwindows yourself inside a main window like e.g. VSCode does with its various panes.