My apologies! It shouldn't be too hard to add fully customizable colors, though probably without a UI (editing an ini file, say). I'll also see what I can do about the default colors for the light style.
* Line numbers will use the same color as the selected text color
* Arrows now have black highlight
* Symbols in gutter are now drawn above selection and are more visible
* Colors for watch-value changed now dependent on mode
* Colors in memory window for highlighted bytes and address now dependent on mode.
If you can notice anything I missed above please let me know.