I would like to propose a removal of the query asking whether I really want to update from source when I press that button on the Book file tab.
I press this button often and it is tedious to have to move the mouse down (a fair way) from the button and then press it and then proceed back to the Viewer tab.
An alternative indicator to indicate that an update was successful could be implemented. Like a red/green indicator above the button - or even colouring the button itself. It would be handy even to have an indication that the file needs to be updated.
I would even propose that the button (also) be on the Viewer tab to make this process even more streamlined.