Confirmed here, too. Design Studio 1.4 Patch 2. Seems like a bug to me.
Add this CSS rule to work around it in the mean time:
#MESSAGE_messageview1_abs {
display : none;
}
EDIT: Seems like this is the application message box that belongs at the bottom right of the DS App. Probably don't want to hide it this way... Hmmm - Will try to think of something else...
Try this instead:
#MESSAGE_messageview1_abs {
width : 0px !important;
height : 0px !important;
}