A separate dialog listing all the events possible that would allow one to set bg and text colors for all of them at the start of the game.
At present, I have to wait for an event to appear before I can color it. This wouldn't be so bad, except I keep my events (ctrl-F3) screen in "SM-view" all the time, even though I run in non-SM mode. The color that display in SM-view are the empire, not SM colors, so in order for new colors to be visible, I have to go to the empire view, change the color, turn on SM-mode (so I can get back to SM-view), set the view to SM-view, then turn off SM-mode.
The other possibility would be to have an SM-view color scheme, and have the changes modify that color scheme when in SM-view.
This is low priority - it's been that way for ages, and I have a practised mechanism for working around it.
John