Like QtExtras: Win, it could be great to add extra items in the dock for your application. The concept is quite similar to QWinJumpList* classes.

For example, iTunes has 4 categories with specific actions or submenus. Also, actions can be disabled, checked, indented, like Now playing with 2 extra indented lines, and have icons. However, in El Capitan, it doesn't seem that actions with icons are still valid anymore (not following the guidelines ?).

See: https://developer.apple.com/library/mac/documentation/Carbon/Conceptual/customizing_docktile/concepts/dockconcepts.html