When holding a (signed & closed) book and right clicking a button, the button is clicked (in this example a button of a command block) and the book is read at the same time.
Not sure if bug or intended.
MC-13435
Right clicking a button with a held book clicks the button *and* reads the book
Resolved
Cannot Reproduce
0
Unable to reproduce neither with book & quill nor signed book, neither button on normal block nor button on command block nor button on command block with teleport command.