Shield - hitting and blocking at the same time

(probably applies to dispensers alone)
When blocking with a shield a dispenser firing at you, pointing to it will open it, but if you still hold down the click, the blocking action will still remain and you can press Esc to exit the dispenser interface and break blocks or hit while still blocking.
Video: https://www.youtube.com/watch?v=DSmPqVN-Ub0