What is this box????

The small rectangular box, I get it quite frequently & can’t tell what it is 

It's telling you your message is too short and cannot be posted. It requires a minimum of 5 characters.

It's telling you your message is too short and cannot be posted. It requires a minimum of 5 characters.

Ahhhhh thanks

[RocketFoot]

Sorry, it reads better on the light theme...I'll have to fix that on the dark theme!