After thinking about I'm really trying to do is create a lightweight round-trip editing cycle.
I used Marked to look at documents and notes that I have created related to my work or projects. Most of the time this is not during the original editing and/or creation process but later on when I'm trying to figure out what has been done or find a fact or two.
It's during this process I find, from time to time, I need to do a little lightweight editing. A period here or a comma or just a quick note to say "Done on the 15th". Currently, I need to open the doc (easy with Command E or click), find the line (more of a pia) and then make the update and save then close the editor. (I know cry me a river)
If I could click on the line (on the margin) :-) and for example HUD (or editing window) would activate with the five or six lines around where I clicked available for editing. Just simple text editing, nothing fancy, but enough to make the change I need, save the file and bring me back into Marked with the changes. This would be ideal.