This makes sense, but why is the toolbar copied to default.rui automatically by Rhino?
The .rui is installed along with the .rhp file, and they have the same name. That's all we do. Then in the "Show Toolbar" context menu action, we activate it.
The toolbar is then always copied automatically to default.rui. If we uninstall the plugin, it stays there. And if we reinstall the plugin, a duplicate toolbar is created. At the end there are many junk toolbars in default.rui and the user has to remove them by hand. That's a terrible user experience.
Is there something wrong we do that causes the copy to default.rui?