This addon will remove the message that is displayed when you hide your UI with the TOGGLEUI binding(default ALT-Z). On enUS clients the message looks like this: "UI Hidden. Press ALT-Z to show it again.".
No more waiting for 2 seconds to take a screenshot after hiding your UI!
Releases can be found here: https://www.curseforge.com/wow/addons/ui-hidden-text-remover