The OS could show a visual indication that it is still running "startup" stuff, which are effectively a part of the boot process. Then you could return once tha

The OS could show a visual indication that it is still running "startup" stuff, which are effectively a part of the boot process. Then you could return once that visual indication is gone, and know that your computer has completed the boot. Currently, the OS simply doesn't tell you when it's actually finished booting.