Aparently, in the lastest snapshot, it is implossible to place any 4x4, 4x2, or 4x3 paintings on minecraft. i tried to fill a wall of açç those dimensions with a single painting. and unlike other versions of minecraft, (in wich the large pic was usualy the first one to be choose)it never placed the ones in this size, even after many tries, and even triyng in bigger spaces. i'm pretty sure this must be a issue from this snapshot, as in all other versions the paintings worked perfectly fine. that's all