Allows using any application you like for opening files in Gnome.
In Gtk+-3.11 (upward) opening files with GtkAppChooser does not allow choosing an application from disk anymore. Gnome people do not consider this a bug, see https://bugzilla.gnome.org/show_bug.cgi?id=650284
Here are two small scripts to circumvent this.
Starts a file selection dialog and spawns the selected file, forwarding its commandline arguments.
Requires pygobject to work. Tested with python-3.5.3 and pygobject-3.22.0.
Place (or symlink) this into ~/.local/share/applications/openwith.desktop or /usr/share/applications/openwith.desktop for a local or global installation. It creates an entry in GtkAppChooser, which will then open openwith.py where you select the application to open your file with.
You need to adapt Exec according to your needs/file locations! The %f is the file name as selected by GtkAppChooser. It is documented here.
Just open an issue and or pull-request. Especially distribution-specific packages might be nice.