I propose the addition of the following property to xfce4-keyboard-shortcuts.xml under xfce4-keyboard-shortcuts->commands->default: <property name="Print" type="string" value="xfce4-screenshooter"/>
It can be a good idea.
Andre Miranda referenced this bugreport in commit ed0c0ddff2926dbf0f8e1abece8a1754e3cd784a Add PrintScreen as shortcut for xfce4-screenshooter (Bug #14524) https://git.xfce.org/xfce/libxfce4ui/commit?id=ed0c0ddff2926dbf0f8e1abece8a1754e3cd784a