Creating a Subsurface bundle

install gtk-mac-bundler (this has been tested with version 0.7.0) and run

gtk-mac-bundler subsurface.bundle

This should install a self-contained Subsurface application under /Applications/Subsurface.app
You still need to manually build a DMG if you want to easily distribute this.

One important caveat is that (at least with MacPorts) you need to build pango like this:

sudo port install pango +builtin_modules +no_x11 +quart

Without the builtin modules the installed application fails to find the modules and doesn't render any text.