I notice when I go to Save a project for the first time, or do Save As..., the first column is not really scrollable.
I for some reason cannot reliably scroll this column (see linked screenshot and arrow) in REAPER. Everything else on my entire computer scrolls OK except this column when I go to Save As... or Save for the first time a new REAPER project.
The times that is does scroll it way slow and I to try really hard for just a little bit of scrolling.
I'm using an Apple Magic Mouse 2.
Screen Shot:
https://www.dropbox.com/s/w9v21qps84...%20PM.png?dl=0