This bug returned is Saucy.
I can confirm this bug in the Ubuntu 13.10 final.
I tried to make a screenshot of a window. So I was going to press <Alt>+<Print Screen> simultaneously.
I press <Alt> (but the HUD opens and got focus) and <Print Screen>. As a result I got screenshot of a HUD, not desired window.
If I run GNOME session flashback I can make screenshot normally. So it is a Unity bug.
This bug returned is Saucy.
I can confirm this bug in the Ubuntu 13.10 final.
I tried to make a screenshot of a window. So I was going to press <Alt>+<Print Screen> simultaneously.
I press <Alt> (but the HUD opens and got focus) and <Print Screen>. As a result I got screenshot of a HUD, not desired window.
If I run GNOME session flashback I can make screenshot normally. So it is a Unity bug.