Currently there is an option to allow scrolling past the last line. This is useful for when I don't want the last line of code to be at the very bottom of my window/monitor. However, after scrolling past the last line if you then execute whatever code is the closest to the last line, the scroll will reset so that the last line is at the bottom of the window. It kind of defeats the purpose.
I get around this by adding 50-100 empty lines after my last line of code, but it would be great if this wasn't necessary and the scroll didn't reset like it does.
The good news is that I filed an issue for this exact reason over at the RStudio GitHub page last October - so they are aware of this issue. The bad news is that it doesn't look like it is in-scope for being fixed in the near future, but it is something they are going to probably fix eventually.