The menu entry "Edit with external tool" should be configurable, because it points to the first configured tool configured to the file extension like jpg or png.
But on Windows if you click on to a picture it starts the pictureviewer normally. But it LibreOffice I wan't to use Gimp for example if the picture in libreoffice is a jpeg file.
The solution would be a additional dialog in which I could choose which tool I like to use.
How about a selection under Tools > Options to not have a nagging dialog?
*** This bug has been marked as a duplicate of bug 51096 ***