The layout of the main window is inconsistent. When removing dock1 and dock2 grouped as one, and putting it back in the main window, the layout option is different depending on what dock is the "main" one from the second window.

This behavior is consistent as switching from dock1 to dock2 will always have the same result. Except if the main dock before undocking them is dock1, but switching from dock1 to dock2 once undocked will reproduce the same behavior*

Layout for dock2 being the "main" one (top)

(bottom)

Layout for dock1 being the "main" one (top)

Layout for dock1 being the "main" one (bottom)