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When the webpage is presented to the user, it tries to show affordances for editing by displaying section borders and the 'close' button, but it is not obvious what editing capabilities are provided or what kind of annotation the user can do. A panel at the top or the side containing all possible editing buttons may improve learnability.
In the collaborative editing mode, it may not be easy for the user to figure out exactly which part is not editable due to other's actions on the same page.
Efficiency:
Safety:
Design 2
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