quickly should support the EDITOR environmental variable.

$ quickly help ubuntu-application edit

Usage: quickly edit



A convenience command to open all of your python files in your project 

directory in your default editor, ready for editing.



If you put yourself EDITOR or SELECTED_EDITOR environment variable, this latter

will be used. Also, if you configured sensible-editor, this one will be

choosed. 

I don't have any other GUI IDEs installed, but I tested it with $ export EDITOR=nano && quickly edit and all files were opened in nano instead of gedit. Adding export EDITOR=nano to your ~/.bashrc should make this change persistent.