Still happens for Disk Cleanup, in a way. It can get stuck at parts, and it might finish but the window doesn't go away until you hover the mouse above it.
Observed the same, it's very annoying. I start a script to image the VM (which among others does disk cleanup before finally handing over to sysprep)... and sometimes I find the unattended VM hours later still waiting for me to move the mouse over the window.
