Steps to reproduce:

• close the door
• walk away from the door
• select nothing in your hand
• point to wherever you want and click and hold right click
• walk to the door while keeping right click pressed and try to point at first to a block next to the door and then mid-walking move your cursor to the bottom of the door
• works only sometimes

--> Cause the door to be optical seperated, though you can walk through it

(trapdoor in the screenshots not related, accidentally opened it)

I'm running server and client 1.8 release.