cannot unmount DMG after installing Qt OSX package and starting creator

1) download the 5.0.0 release package for OSX and install it
2) leave the checkbox enabled to start creator at the end
3) after creator starts, try to unmount the DMG; finder complains that it cannot because it's in use by Creator.
4) quit creator, unmount the DMG and restart creator by finding it on your hard drive

So I wonder if it actually starts creator from the version which is inside the DMG, or it's just that the creator process is a child of the installer, which was started from the DMG. But you'd think if the installer process actually exits, that it would be OK anyway.