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The reason the message "DOCUMENT CLOSED - To keep you focussed.........." is popping up is due to the fact that every change in SuperOffice view will do a call to the Nebula server to render the document again.
Resulting when opening another card, reading a activity like TODO items, diary items, etc will result in a new call to the server to render the document over and over again while your focus is temporary on something different.
Due to the cloud architecture of the Nebula Document Viewer, every new call will cost processor time and data transfer and total cost will go up. That's the reason why this message is coming in to prevent regenerating documents when the focus is on something different.
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