Every vote helps for this dying feature request - also related to prototyping!
Really important for correct usability tests on desktop: Scrollbars in presentation view for scrollable elements. (changeable if they are permanently visible or just when the cursor enters the respective area) is a must when testing for desktop. There is no chance or workaround since no plugins work in this view.
Your vote and/or comment would help a lot: Display scroll bar in prototype preview mode