Do you have any idea why this happened? Can you reproduce the problem? The crash reports should be in ~/Library/Logs/DiagnosticReports/ - can you send them to me?

Mac OS X saves the application state in the folder ~/Library/Containers/com.textasticapp.textastic-mac/Data/Library/Saved Application State/com.textasticapp.textastic-mac.savedState

Deleting that folder would probably have fixed the issue.

Hmm, are you sure this would work and is allowed by Apple? If the installer is launched from within Textastic, wouldn't it inherit its sandbox and thus prevent Authorization Services from working? From the docs: "Important: The authorization services API is not supported within an app sandbox because it allows privilege escalation." See https://developer.apple.com/library/mac/documentation/Security/Reference/authorization_ref/Reference/reference.html

Do you know a sandboxed app on the Mac App Store that includes an installation package?

This should be fixed in Textastic 2.0.

Fixed in Textastic 2.0.

This problem should be fixed in Textastic 2.0 which is now available on the Mac App Store.

You could just open two windows and put them side-by-side.

I'll see what I can do. Maybe this should be the default behavior. I think TextMate does it that way.

Currently, you can do a right-click on the tab and select "Move Tab to New Window". This options only appears when you have at least two tabs in the window though.

What about folders? Is it ok that a folder is added to sidebar in the current window?

By the way: that kind of feedback is very helpful. I had to make some decisions when implementing the sidebar and it's good to know how other people would like the app to behave.