I plan to show a list of recently opened files when you tap on the file name. This should solve the problem.

Adrien's example suggests one example, but those of us who do object oriented programming using a multi-tiered framework like MVC, HMVC, or PAC often need to quickly move between the files of triads to make changes in other files. For example, for an MVC application, you might need to update the Controller file or View file after making changes to the Model file. 

Another example, creating a new Controller file based on an existing Controller file and moving back are forth between the two files while cutting and pasting code. There are an infinite number of similar scenarios where it would be beneficial to have a tabbed interface or something similar. Keep in mind that the two files might reside in different directories making the cut and paste operations very tedious using the present interface.

Did you try to use the list of recently opened files for this? http://www.textasticapp.com/v4/manual/lessons/How_can_I_show_a_list_of_recently_opened_files_How_can_I_close_the_current_file.html

The Recent Files list works as a Recent Files list should. Using Recent Files versus Tabs means an extra keystroke and the time loss of finding the filename. I can live with this for now, but prefer tabs.