Here is an answer to my own posting:
Select Menu > Packages > Settings View > Install packages/themes. A pane will open.
Enter “link” in Install Packages > Search packages. Large buttons open for various packages.
Click the top button, for package “link”. This installs the package silently.
A README is shown, giving the two pieces of information needed to create a keybinding (association of this new command with a keystroke). Make a note of these strings.
Click on Keybindings, to the left of the Readme. Look through the keybindings to choose a free key.
6, Click Menu > File > Keymap. This displays the CSON code for the keybindings.
- Add these two lines:
Indent the second line (not sure if this is needed). Note: I chose to override Ctrl+h.
- Test this new command in an ordinary file. Enter a complete URL, position the cursor in it, and press Ctrl+h. Your default browser should activate, showing the desired URL.
I am also hoping to find a package to open a file pathname at the cursor. Then I can implement projects (lists of URLs and files). It is unfortunate that the interesting functionality offered by packages can only be found at random, instead of the best features being automatically chosen and built into Atom.
This reliance on packages reminds me of TinyMCE, an editor built out of tiny pieces, almost unusable if you don’t have lots of time to spend.