Current questions and answers regarding the map editor.

Yesterday, I performed a similar operation on a randomly generated map in the Dungeon – the result was the same! I deleted a section of the wall between areas; by the way, why can't all walls be selected and deleted? The surface of the area under the deleted wall is exactly the same as the adjacent area – it's level, without obstacles, and has the same pattern – but it's still impassable for the hero.
I would greatly appreciate it if you could provide more details about this impassability check and what this "BLOCKED" area means.
Thank you very much for your help!