I am going to use a textured patterned paper for my sitting room wall (before I just put up lining paper and painted it). I have now got a problem as one external corner is not straight, so if I use the patterned paper, it will not wrap around that edge well, and the pattern will not look alright. The edge looks fine until about half way down the wall, then it curves in for a few inches downwards and then curves back out again (to the top of the skirting). Instead, of messing around trying to build the edges of the wall up here, is there something that can be fixed to this external corner (from ceiling to skirting) that is extremely thin (a bit thinner than a length of PVC tile trim), so that I can then go ahead and paper over it (so that there is a nice neat edge on the corner)? Any ideas would be appreciated. Thank you.