public static void HighlightCharacterAt <TFont, TGlyph>(this FractionDisplay <TFont, TGlyph> self, MathListIndex index, Color color) where TFont : IFont <TGlyph>
{
if (index.SubIndexType != MathListSubIndexType.None)
{
throw Arg("The subindex must be none to get the highlight a character in it.", nameof(index));
}
self.Highlight(color);
}
