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You can already add custom themes to Textastic. This is explained in the manual: http://www.textasticapp.com/v4/manual/lessons/How_...

The "Mac Classic" theme can be found here: https://github.com/kballard/textmate-bundles/blob/...
TextExpander had to change the mechanism that is used to exchange snippets with third party apps. See http://smilesoftware.com/blog/entry/important-chan...

Textastic doesn't use the latest TextExpander SDK yet, so TextExpander doesn't currently work in Textastic. It will be fixed in the next update.
I found the problem: when Textastic sees a setting dictionary that doesn't contain a name and scope, this is considered to be the global theme settings dictionary that defines things as the selection and caret color.

In line 368 ( https://github.com/mekwall/obsidian-color-scheme/b...) there is an empty dictionary. So Textastic ignored the real settings dictionary and used the empty settings dictionary from line 368 instead.

Remove lines 368 and 369 from the theme file and it works!
if the theme contains a "caret" color, this is used instead of the "selection" color. So it should work if you change the "caret" color of the theme.
Sorry, but can you please give me more details about what you want to know?
I've changed the behavior so that in the next update, they additional keys are always visible even when an external keyboard is connected. On iOS 7 it is no longer possible to reliably detect if an external keyboard is connected or not. You can hide the additional keys in the settings screen.
Yes, this is a bug that is caused by a change in how iOS 7 handles external keyboards. It will be fixed in the next update.
Does this happen with all text you try to copy from Safari or is there content (maybe without formatting) that you can copy and paste into Textastic?
iOS 7 brought a lot of changes regarding keyboard handling.

This will be fixed in the next update: the additional keys will always stay on the screen, but you can disable it in settings and the UI will be completely usable even with the additional keys displayed.