Feature: (Auto)save whiteboard in nextcloud files

I installed the whiteboard app without the collab backend. I opened a new whiteboard and did some edits. Although the app creates a new .whiteboard file it always remains empty. 
I thought the app saves the edits automatically to the .whiteboard file but when I  reopen the browser and the file it is an empty whiteboard.
Would be very helpful to have a (auto)save functionality.
