I think this has already been fixed in KES. They seem to have had compatibility issues with scripts that add icons to the toolbar menu. I was going to look into it today, but as far as I can see, things seem to be working at the moment (except for some overlapping functionality that probably shouldn't be enabled at the same time).
It's a great project they're working on and I don't rule out anything of course, but I feel that it somewhat goes against the very reason why I'm doing this. I see KUP as essentially a personal test bench to try out some new stuff without having to deal with code reviews or CCBs. The end goal is to see what works well and then port that functionality over to the Kbin core project.
As you might have seen, I've already ported parts of the KUP style settings panel to Kbin, and I have some more projects in the pipeline (that is if they are accepted into the project, which is not guaranteed of course).