I am submitting a feature request here, because the page to do feature requests does not work (https://visualstudio.uservoice.com/forums/293070-visual-studio-code).
My feature request is for a horizontal split in addition to a vertical split. Currently, you can only view tabs next to each other, but I'd like to be able to view them top and bottom. This would be especially helpful when you have files that have really long lines of code.