Your comments

Thanks. Similar buttons were already used in the apps "Heart Writer" and "FlickKey", so I can't really take credit for the original idea. But I've put a lot of thought in the arrangement of the keys in Textastic.
The right and left arrow idea sounds good. I'll try it out.
Unfortunately, this bug was introduced in the latest version.

The crash happens when you try to delete the currently open file. As a workaround, you can close the file first and then delete it: 
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


I will fix it in the next version.
It shouldn't. Which version do you use? Which iPad? 

I'll consider it. It just never happened to me that I accidentally started zooming.
This already exists in the form of the symbol list.