What is sandboxing?

NOTE: This is older information. Most of it is still correct in terms of Apple's restrictions, but Composer is now up to version 4. It has improved sandboxing support, but the rules still exist. If you have issues related to sandboxing, let me know. Thanks!

Apple has begun to require that all applications sold through the Mac App Store are "sandboxed" — this means that the application has limited access to the files and processes on your computer. The motivation behind this requirement is likely a good one — to help prevent maliciously designed software from accessing or damaging your information. The problem is that it restricts the features that are available. This includes MultiMarkdown Composer.

(NOTE: MultiMarkdown Composer versions 2.1 and above have new features that will work around some of the limitations of sandboxing when previewing local images, using BibTeX files, etc. Close the file you are working on, and then reopen it after adding local URLs. Composer will ask for permission to access the folder containing these files.)

For example, MultiMarkdown Composer users frequently want to see a preview of how their document will look when rendered as HTML. These HTML files will often include images, links to CSS files, etc. If these files are specified as URLs from the internet (e.g. http://example.com/image.png), everything will work just fine. If the links are specified as local URLS (e.g. ../images/image.png), the sandbox permissions will not allow Composer to open that file, since the user did not specifically grant permission to open those files.

Composer can be used to open image files, which would then enable access permission when used in a preview. But this can be a frustrating experience to remember to open each and every image each time you launch the applications.

Because of these limitations, you can download a version of MultiMarkdown Composer that has been compiled without sandboxing. You are still required to purchase Composer through the Mac App Store, but your license will be recognized by the alternate version as well. The download is available from the MultiMarkdown web site.

You cannot purchase the non-sandboxed version directly. All purchases are made through the Mac App Store. Once purchased, you will also be able to use the non-sandboxed version when you download it.

Features that are blocked by sandboxing:

• display of images and other files in the web preview
• reading BibTeX files to show the citation keys in the References HUD
• mmd_merge is not compatible with sandboxing
• customizing the key commands for menu items in the app

Features that are only available in the Mac App Store version:

• Due to restrictions in place by Apple, only the MAS version has access to iCloud for document storage. If you plan on using iCloud, you will want to use the App Store version. The good news is that apps have "free reign" inside their iCloud Documents folder — this means that the sandboxing restrictions won't affect your documents stored here. MultiMarkdown Composer for iOS is still under development, but when it's finished iCloud will be a great way to have access to your documents on all of your Apple devices.

If you install both the sandboxed and non-sandboxed versions, they will use separate preferences.