The latest version of Textastic (5.2) is updated for the higher resolution of the iPhone 6 and iPhone 6 Plus.

You can create a new file locally and then upload it to Dropbox using the file transfer screen (globe icon). 

For more info, have a look at this entry in the Trxtastic for iPhone manual: http://www.textasticapp.com/iphone/v5/manual/lessons/How_can_I_download_or_upload_files.html

Do you have a link with more information?

I plan to submit it to Apple this week. 

What exactly is the error message? 

Please try to enable the "Debug Log" setting in the connection's settings screen. Tap on the (i) button on the right side of a connection to change its settings. This creates a log file when you try to connect to the server which might help you find out what's wrong.

Yes, unfortunately this is a bug in the latest iPad version of Textastic. It will be fixed in the next update. Sorry for the inconvenience!

You can create and edit HTML and JavaScript files in Textastic and preview them locally using the built-in preview functionality. This does execute the JavaScript part.

I had a look at Meslo. It looks like the author just took Apple's font and modified it. Menlo is copyrighted by Apple, so that sounds fishy...

It seems like iOS 8 includes Apple's Menlo font though, so I plan to include that.

Well, I added external files that are opened through the "Open…" command to the recent files list exactly for that reason. If the file does not exist anymore, it is not displayed in the list of recent files.

I figured it would only confuse the user if external files shows up next to iCloud files, especially if you have a lot of files in iCloud.

I would also like to display more information in the recent files list (like the file path or external app name), but this information is not available with the current iOS APIs.