SnapOpen (http://github.com/MadsBuus/gedit-snapopen-plugin) and other forks use Ctrl+Alt+O to open files, so there is a conflict between SnapOpen and Zen Coding. In order to have both plugins working, I usually fix this issue editing plugin.py and changing the shortcut for Zen Coding to Ctrl+Shift+Alt+O. I think it would be good to have this by default.
SnapOpen (http://github.com/MadsBuus/gedit-snapopen-plugin) and other forks use Ctrl+Alt+O to open files, so there is a conflict between SnapOpen and Zen Coding. In order to have both plugins working, I usually fix this issue editing plugin.py and changing the shortcut for Zen Coding to Ctrl+Shift+Alt+O. I think it would be good to have this by default.