I'm running Linux Mint 18.3 MATE, though I imagine an answer to this question would easily be ported to Ubuntu or Debian.
When I'm in an application, I can hit Ctrl-O to bring up the 'Open File' dialog box, and the chosen file will open in the current program. It's the same dialog for every program.
I'd like to be able to hit Super-O to pull up this dialog and open a file from anywhere, in its default application.
I know I can go to "Menu>Keyboard Shortcuts" to run a bash script with Super-O, so is there a way to use the terminal to pull up this dialog and do
xdg-open to the chosen file?