Great to hear!
Yes, so if you hold down CTRL or CMD when you drag an area, that's the 'tile' based mode for most tools. So with the marquee/select area it'll do it by snapping to tiles rather than pixels, and for fills like the dither, or shapes, it'll do it snapping to tiles. Hopefully that solves your problem, but I'll also add mouse clicks outside of the canvas to the list too.