I'm trying to find out how to change the color used for bookmark symbols and modified line numbers, but seems there is no way to do that.

Using bold numbers instead of colored stripes to indicate changed lines is not a bad idea per se. Unfortunately EmEditor uses same font for line numbers and code window and the use of monospaced fonts (common practice when coding) makes almost impossible to visually distinguish between bold and regular.

Why not allowing user to define a different typeface for line numbers and code window or at least the color and style used for bookmark symbols and changed line numbers?

Thanks!