When OverviewControls goes from HIDDEN to APP_GRID, it constantly checks if AppDisplay needs to be visible or not by checking the current overview state is bigger than WINDOW_PICKER. Turns out in this case this check is problematic, because when the current state trespasses WINDOW_PICKER, the layout manager will have already positioned AppDisplay halfway to its final position.
Use either the final or the current state, whichever is biggest, when updating the AppDisplay visibility. It optionally allows passing the overview state params to _updateAppDisplayVisibility() so that we avoid a few trampolines to recaltulate the adjustment state.
Sorry this is a bit hard to describe in words, here's a quick video of the problem: