Textra is a wonderful, feature-rich app and my preferred SMS/MMS app: however, it's missing a few features. One of those is supporting the special screen modes that some make Android phone manufacturers have, such as Samsung's (and I believe LG's) split-screen mode, and Samsung's multi-view, pop-out, minimized, air view, and other specialized screen modes.

Split-screen view is coming to the Android ecosystem inn the anticipated Nougat release of the operating system. It makes sense for Textra to also support at least the most common of the manufacturer's enhanced screen modes.