Too Long; Didn't Read
In TextMate 2, by default, the Ruby code has a highlighted background, so although it may not look attractive, it is swift to see. Sublime Text 3 does highlight the embedded Ruby code, but does not highlight Ruby code. Visual Studio Code does not have the Ruby on Rails file type, so all files must be opened in plain Ruby mode. Atom has the opposite behavior, and it opens all the.rb files in this mode in Ruby on.rb mode, but it does not remember the type manually selected.