UV, Modify UV island when modifying mesh I saw somewhere that there was an option in Blender that allows you to modify the UV map at the same time you modify the topology of the object.
I remember seeing a video where a box working as a wall had some faces extended to make the wall larger. In that video, the UV islands for those walls extended at the same time so the texture proportion wasn't affected.
I can't find how to do it?
Apologies if I have just dreamed it but I remember clearly and it is really frustrating I cant find how to do it after googling for a while.
Maybe you're talking about the Correct Face Attributes option which will change the UV as soon as you change the topology:

Also, when you slide an edge, make sure you have the Correct UVs option enabled in the Operator box: