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There was a crash under iOS 7 which was fixed in the latest iPad update. I plan to release an update of the iPhone version in a few weeks. This should fix the problem on your device.
Undo and Redo buttons do come up when the editor has focus (keyboard is visible).
I can reproduce the problem and will try to fix it.
What kind of files are you editing when this happens? Are you typing with an external keyboard or with the one-screen keyboard?
Hello, you can add custom syntax definitions to Textastic by using TextMate bundles. See
A quick search for "GLSL tmbundle" in Google brought up this TextMate bundle which should work:
HTML 5 animations should already work.
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So the symbol list would need to be much smarter and actually evaluate the LaTeX code to display something more sensible.