After sending the feedback to Google – which even if they will consider it, it will take a while to get it in – looking for ways to change and customize the Dynamic Views I found a lot of useful tips at http://www.southernspeakers.net/, all by simply by using additional custom CSS styles.
Then it hit me, I may be able to force the vertical scrollbar with CSS code! The solution is not perfect, as it is only renders the scrollbar for as many entries as configured to load in a batch, but it’s something and sort of plants the idea that there are more posts in there.
You can add the custom CSS style in Blogger in Template > Customize > Advanced > Add CSS.
div#sidebar { overflow-y: scroll !important; }http://www.w3schools.com/cssref/css3_pr_overflow-y.asp
http://www.w3.org/TR/CSS21/cascade.html#important-rules
As a tip, you can find these bits with F12 developer tools (very similar in all current browsers) and then use the pointer in the toolbar to focus the element you want to work with.