I can share my experience with this as well, I like to play (can you tell 🙂).
I don´t know how comfortable you are working with CSS? I have played around with the menu bar and it is possible to change color etc. of the bar BUT this unfortunately also change the color of many other areas throughout Aware IM e.g. bars top/bottom in forms and queries. I suppose it´s possible to rework/rewrite the css so the top bar use 1 css class and all other bars use another class but I haven´t tried it. I have done a couple of other changes with theme specific css and it SEEMS as though it´s possible to do whatever you want but it´s a bit of work and some css skills are required.