OS X disables click-through by default (see https://stackoverflow.com/questions/23156386/mac-clicking-between-programs-requires-2-clicks), however individual programs can enable it.
I find that I often have my cursor in the editor, than move to a different program (probably copy-pasting from stack exchange 
) and then come back and want to work in the console. Clicking the console will bring RStudio to the front, but the cursor is still in the editor, not the console where I clicked.
Maybe this is only an issue for me because I came from PC, but I find this behavior really annoying (and to be clear, it is OS X's fault, not RStudio's). I'll start typing and not realize I"ve screwed up my editor file.
I think it would be great if click-through were enabled on RStudio for mac so that when we come back from another program, the cursor goes to where we click the first time.
(If anyone has any workarounds or knows of third party programs that can allow this behavior, I'd love to hear that as well).