So, what is this orange bar???? It sort of detracts from the view.
This shows the current selection of an instrument in the Rack. The one which is selected is reflected in the virtual MIDI keyboard as well.
I am no expert but to me it looks as if when you collapse the instrument to the right and then have the library shown to the left then you can drag and drop the NKI from left to right , then when having more (a multi ?) then you can select either , which will reveal that the vertical 'orange bar' signifies 'selected' instrument and at the same time then selecting will show the instrument key range below.
got it. Took me a minute to understand the first answer. Lol