code0:
When shutdown in flight, you always want the prop to feather to a minimum-drag angle. With many free-turbine installations this is automatic, and happens as the fuel lever is moved to the shutdown (or stopcock) condition.
But with a single-shaft machine, some separate action (another handle or button or ...) is required to move the prop to feather, since a standard ground shutdown would place it in flat pitch. Maybe someone else can step forward with specific examples of how this is controlled in the cockpit.
BTW - there is a minor variation on the feathered blade position. The Dowty prop (e.g. Saab 340/CT7) goes to a nearly-feathered position called "autocoarsen"; instead of stopping rotation completely, the prop slowly windmills. This is allegedly a lower-drag condition than fully feathered. This is merely a footnote to your blade-angle diagram, and I wouldn't necessarily make a big deal of it.