How to pipe program output in an editor?
To do this all in one line with any editor, create a temporary file, open it with gedit, then delete it once gedit has it open:
echo hello > temp ; gedit temp ; sleep 1 && rm temp &
The following works with an editor such as vim, but gedit, geany or emacs seem to be unable to open standard input or temporary files as created by <( )
vi <( echo hello )
echo hello | vi -