I tried the split view today and while I had hoped it would be helpful as I was making a purchase on a meal order site it just made things a mess. I had my cart in one tab and the available menu on the other. However the problem was on the menu tab there are filter options to select. If you have that tab full screen these checkboxes are in the sidebar but since it was in the split view Firefox pushed them to the top of the screen and the text went over the images of the available menu choices. There also was no way to close/compress the checkboxes so I could see the images without the text overlaying everything. Not good. Something like this definitely needs looked at for a future update to improve the split view.
