That comment is 7 years old. I clicked around in Xcode for a bit and it doesn’t anymore.
I didn’t expect “I can’t click “Open Downloaded File” on a file downloading application because the scroll bar is in the way” would generate any discussion. It should be obvious to everyone that it’s an issue and should be fixed.
If you know how to fix it (even if just by written word), please do help them to fix it by sharing the solution, as you don't seem to be the only one who is disturbed by the issue.
What about Xcode? According to the PR where they tried to solve it (https://github.com/transmission/transmission/pull/1), it seems it suffers from the same problem.