I've painted the backsplash behind my sink and kitchen counter and want to finish it off with a border of mosaic tiles, 1 or 2 tiles high on the 'pillar' areas in the pic (there is a 3rd one to the left, not seen in pic) - from inside the window and around the pillar, above the paint line. My question is, could I just glue the tiles on, or do I need to go through the whole rigmarole of tile adhesive and grouting - and if the latter, how do I do that without creating a mess of adhesive/grout that needs painting over? In other words, how do I do this tiny tiling job without needing to paint over anything afterwards?