errors with libgtk preventing install

[Bryce Holcomb]

Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help resolve the situation:

The following packages have unmet dependencies:
 vocal : Depends: libgtk-3-0 (>= 3.14) but 3.12.2-0ubuntu15.2 is to be installed
E: Unable to correct problems, you have held broken packages.

[Nathan Dyer (nathandyer)]

Hi! Vocal requites Gtk+3.14 or higher. You only have version 3.12 installed. You'll need to either update your version of Gtk (not recommended), or try Vocal on another platform that has that version installed.

Cheers!