Add node to the polygon of a room's floor

[rexkogitans]

When my plan was nearly ready, I realised that I forgot a corner. I drew the additional two walls, but now I need to modify the polygon of the floor. I needs an additional node. How can I do this without deleting and re-drawing the room?

[Mike53]

Select the room > right click near your new walls > select " add point to room > drag the new point to the new corner. you can delete or create as many points as needed
Or
Select the room tool and draw another room in the area needed, then modify it to match the existing room.
1st option would be better though.