Make Minimize chat button less obtrusive

[jpd236]

Minor issue, but someone on our team reported that the position of the new Minimize chat button was slightly distracting, in that at least once or twice it covered up a row number that needed to be clicked and dragged. A couple of ideas:

1. Could the button be made more minimal (and perhaps expand out upon mouse over) so it's not as prominent when not in use?

2. Could we consider moving the button up the page so it's in a less critical area, e.g. at the top of the frame where there's some whitespace left of the "File" menu and search icon?

[zarvox]

+1 to both of these ideas. I had a similar experience and also noted the free space at the top of the Sheets frame as being likely less conflict-prone.