I guess you can add this to the list. To open a file in an external editor:
Settings > Tools > External Tools > Add new (Plus)
Enter name and description and then in the Tool Settings enter the path to the executable for the program you want to open the file with.
In the parameters insert $FilePath$ which can also be found by using the “Insert macro…” button.
Finally enter $ProjectFileDir$ in the Working Directory field which can also be found using the “Insert macro…” button.

You can uncheck “open console” so the console doesn’t open every time you open a file in your external editor.

Since Intellij Idea is awesome, you can assign a shortcut to your new external tool:
Settings > Keymap > search for the name of the external tool you entered above. Double click on it and set a shortcut for it.