CONNECT's Customize Ribbon box: How to remove old buttons from "Choose components from:" list?

Hi, folks. I'm looking to create some ribbon buttons in a dgnlib file and load it via MS_GUIDGNLIBLIST. The loading works fine. The question I have is about how to get rid of old button definitions that I created and no longer want anymore.

VERSION INFO
MicroStation CONNECT 10.0.0.25

STEPS TO REPRODUCE
1. Open the dgnlib pointed to by the MS_GUIDGNLIBLIST variable in MicroStation.
2. Right-click on ribbon and choose "Customize Ribbon".
3. In the Customize Ribbon box that appears, create a new ribbon tab on the right. I've been using the "Drawing" group for this.
4. Create a group in that new ribbon tab.
5. Create a button in that ribbon.
6. Now observe that that ribbon button's name shows up over on the left in the "Choose components from:" list. Okay so far.
7. Delete the button you just made on the right. Let's say you're deleting it because you changed your mind, decided to go in a different direction, whatever. Button is deleted on the right. Push {Apply}. Even exit MicroStation if you want.

THE PROBLEM
Now comes the problem that I don't know how to solve: The now-deleted button is still listed on the left, in the "Choose components from:" list. I have some buttons I tried creating a few times and they're all over in that list, cluttering it up.

How can I get entries for already-deleted buttons removed from the "Choose components from:" list in this Customize Ribbon box?
Is there some key-in to purge these? Compressing the dgnlib (with all checkboxes on) did not get rid of them.

Thanks for any help you can provide.