Rhino toolbars and toolbar collections are created with Rhino. Check the online help for the
Toolbar command. Basically, you want to create your own .RUI file that contains your toolbars and toolbar collections.
Rhino can automatically load an .RUI file for your plug-in if you provide one.
The first time a plug-in is loaded, Rhino looks for an .RUI file with the same name as the plug-in .RHP. If it is found, it is copied to the
%APPDATA%\McNeel\Rhinoceros\5.0\Plug-ins\[plug-in name] ([plug-in UUID)\settings folder and opened. It is copied, or staged, to ensure that it is writable and to provide a way to get the default one back.
You can get the default .RUI file back by deleting the RUI file in %APPDATA% and restarting which will cause Rhino to copy the file again since it no longer exists.
All that being said, there is additional code in Rhino that saves the name of .RUI files closed by the user. If a user closes a .RUI and the .RUI file is associated with a plug-in, the file name goes on a list so that Rhino does not automatically open the .RUI file in the future. The logic is if the user closed the file, we don’t want to keep loading it every time Rhino starts.
Does this help?