Continuing the discussion from Previously reported R8 UI issues still present:
I agree this needs to be improved. After the launch of Rhino 8 things have undergone changes and are still being worked on. This also means that the help files need to be rewritten. Once the changes to toolbars are done, this work can be started. I’m notifying @KelvinC as well.
In the meantime:
the term ‘linked RUI file’ is basically a Rhino .rui file that is linked to Rhino. An RUI file stores buttons/macros, toolbars, toolbar groups and optionally menu items.
If you install a plugin, this plugin, if it has toolbars, will have their own RUI file(s) that are installed with the plugin. The visible part of that RUI file are the toolbars, buttons and optionally the plugin’s dedicated menu item(s)
Next to that, if you create new RUI file in Rhino, and create your own set of macros/buttons in that RUI file, you can store these macros/buttons and any toolbars you create from these, as well as an optional menu in that RUI file. This RUI file can be opened through Optins>Toolbars>File>Open (in Rhino for Windows it can also be dragged into the Rhino viewport to install, but that currently doesn’t work in Rhino for Mac)
So in short, an RUI file is a library of macros/buttons, toolbars and toolbar groups.