In the sample text box, when I enable the grid, sometimes the gridlines pass right through the characters. For example, the default settings (Neon, size 16, weight 300, width 100, slant 0, texture healing on (or off), ligatures on), in the line "// Implement timing", the gridlines encroach on charcters in "Implement" and clearly intersect characters in "timing".

If it's just an issue with the textbox, it doesn't matter. If it's an issue with the monospaced font, that's a problem.