"After this I looked, and behold, a door standing open in heaven!" - Revelation 4:1
A DOOR IN HEAVEN...is where the current revelation that you have is sufficiently understood and lived out. You can see the walls of your current paradigm, but then a door opens up and you see into a greater dimension.
John was in a heavenly realm, and then he saw a door opened (some call it a portal). He had reached the full capacity of revelation and experience. He could see the walls, the boundaries, the limitations of his current level of spiritual experience.
He had heard the prophetic word to the seven churches, but there was more. There is always more! There is a door opened to go from one glory to another glory.
Do you feel as if you have hit a wall? Most likely you have, but there will be a door that you can pass through to something greater, deeper and fuller. If you have hit the wall, ask Holy Spirit to show you the heavenly door...