I have found a slightly annoying issue in layouts.
If you change the display mode of a detail view to something else than Wireframe, and you then hit space/Enter/right click by accident, then this calls the SetDisplayMode command again, but inside the main layout window.
However it’s impossible to change this back in the menu. The only way is to call the command again, which is usually not the usual way display modes are changed.
Beginners found this very hard to identify (what have I done to create the problem ?) and troubleshoot (how do I change this back ???)
The display mode should either be available in the dropdown menu of the main layout window, or this command should be disabled in such a viweport so this issue doesn’t happen in the first place.