Snapping to Hex Grid

I use an H hex grid for my hex crawl game and I would like to draw my terrain in since the other options are not so great. I try drawing terrain colors into the existing gridlines, but it's sloppy since it doesn't snap (for some reason it only snaps to square grids). Any way to fix this? Note: I am NOT looking for alternatives to creating maps the drawing tool, just ways to draw more precisely.

At this time there is no snap to hex intersection function. What you could do is zoom in to more precisely place the lines.