Just buy a long mirror with a big frame and prop it up against the wall from an inch or so away. If it's heavy enough, it'll never budge. Just make sure you don't lean on it... :)
Hi,
I recently redecorated our bathroom, repainting the entire room and regrouting the original tiles.
Our bathroom has tongue-and-groove cladding all round and, above the cladding as it goes around the bath, tiling in white half-tiles to the ceiling.
After painting the woodwork...