On the iOS app when I am selecting a highlight there are "icons" for custom highlights. Example:

I suppose these aren't technically icons, but they function in place of an icon. However, in the Windows program there is no icon for custom highlights. What I end up seeing is something like this:

I have to hover the mouse over each one and then read which highlight it is. It would be much more convenient if the Windows program incorporated some visual cue similar to the iOS app.